Dell EMC VxRail Appliance TechBook

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DELL EMC VXRAIL

APPLIANCE

Hyper-Converged Infrastructure Appliance from

Dell EMC

®

and VMware

®

ABSTRACT

This TechBook is a conceptual and architectural review of the Dell EMC VxRail

Appliance. It presents industry trends towards converged infrastructure and focuses on the VxRail Appliance as a leading hyper-converged technology solution.

November 2016

TECHBOOK

VXRAIL CONCEPTS AND ARCHITECTURE

The information in this publication is provided

“as is.” Dell Inc. makes no representations or warranties of any kind with respect to the information in this publication, and specifically disclaims implied warranties of merchantability or fitness for a particular purpose.

Use, copy, and distribution of any software described in this publication requires an applicable software license.

Copyright © 2016 Dell Inc. or its subsidiaries. All Rights Reserved. Dell, EMC, and other trademarks are trademarks of Dell Inc. or its subsidiaries. Other trademarks may be the property of their respective owners. Published in the USA. 11/16 VxRail TechBook H15104.3.

Dell EMC believes the information in this document is accurate as of its publication date. The information is subject to change without notice.

VXRAIL CONCEPTS AND ARCHITECTURE

PREFACE ..................................................................................................................................6

Audience ........................................................................................................................................... 6

Related Resources and Documentation ............................................................................................ 6

Contributors ....................................................................................................................................... 6

Conventions ...................................................................................................................................... 7

INTRODUCTION ........................................................................................................................8

Deployment Trend Towards Converged Infrastructure (CI) ............................................................... 8

Design Trend Towards Software-Defined Data Centers (SDDCs) .................................................... 8

Hyper-Converged Infrastructure ........................................................................................................ 9

DELL EMC CONVERGED-INFRASTRUCTURE PLATFORMS OVERVIEW ....................... 12

Block Architecture ........................................................................................................................... 13

Rack Architecture ............................................................................................................................ 13

Appliance Architecture .................................................................................................................... 14

VxRail Product Profile ..................................................................................................................... 15

VXRAIL HARDWARE ARCHITECTURE ............................................................................... 17

VxRail Appliance Cluster ................................................................................................................. 18

VxRail Node .................................................................................................................................................................. 18

VxRail Node Storage Disk Drives ................................................................................................................................. 20

VxRail Networking ........................................................................................................................... 20

1GbE Network Option ................................................................................................................................................... 22

VxRail Models and Specifications ................................................................................................... 22

VxRail Scaling............................................................................................................................................................... 24

VXRAIL SOFTWARE ARCHITECTURE ................................................................................ 26

Appliance Management ................................................................................................................... 26

VxRail Manager ............................................................................................................................................................ 26

Vision Intelligent Operations ......................................................................................................................................... 28

VMware vSphere ............................................................................................................................. 28

VMware vCenter Server ............................................................................................................................................... 29 vCenter Services and Interfaces .................................................................................................................................. 30

Enhanced Linked Mode ................................................................................................................................................ 32

VXRAIL CONCEPTS AND ARCHITECTURE

VMware vSphere ESXi ................................................................................................................................................. 32

Communication between vCenter Server and ESXi Hosts .......................................................................................... 33

Virtual Machines ........................................................................................................................................................... 33

Virtual Networking ........................................................................................................................................................ 35 vMotion and Virtual Machine Mobility ........................................................................................................................... 36 vSphere Distributed Resource Scheduler .................................................................................................................... 38 vSphere High Availability (HA) ..................................................................................................................................... 40 vCenter Server Watchdog ............................................................................................................................................ 42 vSAN ............................................................................................................................................... 43

Disk Groups .................................................................................................................................................................. 43

Hybrid and All-Flash Differences .................................................................................................................................. 46

Flash Endurance .......................................................................................................................................................... 47

Client Cache ................................................................................................................................................................. 47

Objects and Components ............................................................................................................................................. 47

Storage Policy Based Management (SPBM) ............................................................................................................... 48

Sparse Swap ................................................................................................................................................................ 52

I/O Paths and Caching Algorithms ............................................................................................................................... 52 vSAN High Availability and Fault Domains ................................................................................................................... 57 vSAN Stretched Cluster ................................................................................................................................................ 58

Snapshots ..................................................................................................................................................................... 60

Storage Efficiency Using Deduplication and Compression .......................................................................................... 63

Erasure Coding ............................................................................................................................................................. 65

SUPPORT FOR EXTERNAL NETWORK STORAGE ........................................................... 69

ISCSI with VxRail ............................................................................................................................ 69

NFS with VxRail .............................................................................................................................. 69

INTEGRATED SOLUTIONS ................................................................................................... 71

VMware Horizon .............................................................................................................................. 71

VMware Horizon with VxRail ........................................................................................................................................ 71

Native Hybrid Cloud (NHC) with Pivotal Cloud Foundry .................................................................. 72

VxRail VM Replication ..................................................................................................................... 73

VMware vSphere Replication ....................................................................................................................................... 73

Dell EMC RecoverPoint for Virtual Machines ............................................................................................................... 74

VxRail Replication Use Case ........................................................................................................................................ 75

Storage Tiering and File Support with CloudArray .......................................................................... 75

VXRAIL CONCEPTS AND ARCHITECTURE

Integrated Backup and Recovery with vSphere Data Protection (VDP) .......................................... 77

VXRAIL SERIES USE CASES ............................................................................................... 79

Use Case: Platform as a Service (PaaS) ........................................................................................ 79

Use Case: Hybrid Cloud .................................................................................................................. 80

Use Case: Analytics and Collaboration ........................................................................................... 81

Use Case: Server Workloads .......................................................................................................... 81

Use Case: End User Computing Services (EUC) ............................................................................ 81

VxRail Advantages for VDI ........................................................................................................................................... 82

Meeting the Virtualization Challenge for Federal Agencies ......................................................................................... 82

Use Case: Simplifying the Distributed Enterprise Environment ....................................................... 83

VxRail Appliance Advantages for Distributed Enterprises ........................................................................................... 83

Meeting the Distributed Enterprise Challenge for State and Local Agencies .............................................................. 83

PRODUCT INFORMATION .................................................................................................... 85

Product Support .............................................................................................................................. 85

Dell EMC Professional Services for VxRail Appliances ............................................................................................... 85

Customer Upgradeable Software ................................................................................................................................. 85 vSphere Ordering Information ...................................................................................................................................... 86

PREFACE

This Dell EMC TechBook provides a thorough conceptual and architectural review of the Dell EMC VxRailTM Appliance. It reviews current trends in the industry that are driving adoption of converged infrastructure and highlights the pivotal role of

VxRail in today’s modern data center.

As part of an effort to improve and enhance the performance and capabilities of its product lines, DELL EMC periodically releases revisions of its hardware and software. Therefore, some functions described in this document may not be supported by all versions of the software or hardware currently in use. For the most up-to-date information on product features, refer to the product release notes. If a product does not function as described in this document, please contact your Dell EMC representative.

Audience

This TechBook is intended for Dell EMC field personnel, partners, and customers involved in designing, acquiring, managing, or operating a VxRail Appliance solution. This TechBook may also be useful for Systems Administrators and Dell EMC Solutions

Architects.

Contributors

Along with other Dell EMC and VMware engineers, field personnel, and partners, the following individuals have been contributors to this

TechBook:

Curtis Edwards

Hanoch Eiron

Flavio Fomin

Colin Gallagher

Sam Huang

Bill Leslie

Arron Lock

Jason Marques

Megan McMichael

Jeremy Merrill

Gail Riley

Joe Vukson

Jim Wentworth

Violin Zhang

VXRAIL CONCEPTS AND ARCHITECTURE

Aleksey Lib

Conventions

Dell EMC uses the following type style conventions in this document.



Normal

—Used in running (nonprocedural) text for: o

Names of interface elements, such as names of windows, dialog boxes, buttons, fields, and menus o

Names of resources, attributes, pools, Boolean expressions, DQL statements, keywords, clauses, environment variables,

 functions, and utilities   o

URLs, pathnames, filenames, directory names, computer names, links, groups, file systems, and notifications  



Italic: Used in all text (including procedures) for:  o

Full titles of publications referenced in text o

Emphasis, for example, a new term o

Policies and variables

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Courier

—Used for:   o

System output, such as an error message or script   o

URLs, complete paths, filenames, prompts, and syntax when shown outside of running text 

VXRAIL CONCEPTS AND ARCHITECTURE

INTRODUCTION

The IT infrastructure market is undergoing unprecedented transformation. The most significant transformation is reflected by two major trends: a deployment trend toward converged infrastructure and a design trend toward software-defined data centers (SDDCs). Both are responses to the IT realities of infrastructure clutter, complexity, and high cost; they represent attempts to simplify IT and reduce the overall cost of infrastructure ownership. Today’s infrastructure environments are typically comprised of multiple hardware and software products from multiple vendors, with each product offering a different management interface and requiring different training. Each product in this type of legacy stack is likely to be grossly overprovisioned, using its own resources (CPU, memory, and storage) to address the intermittent peak workloads of resident applications. The value of a single shared resource pool, offered by server virtualization, is still generally limited to the server layer. All other products are islands of overprovisioned resources that are not shared.

Therefore, low utilization of the overall stack results in the ripple effects of high acquisition, space, and power costs. Too many resources can be wasted in legacy environments.

Deployment Trend Towards Converged Infrastructure (CI)

Industry-infrastructure deployment has shifted from a build to a buy approach. This shift is being driven by the need for IT to focus limited economic resources on driving business innovation. While a build-your-own strategy can achieve a productive IT infrastructure, these deployments can be difficult and lengthy to implement and vulnerable to higher operating costs, and they’re susceptible to greater risk related to component integration, configuration, qualification, compliance, and management. Converged infrastructure (CI) packages compute, storage, and networking components into a single optimized IT solution. CI is a simple, fast, and effective alternative to build-your-own and has been widely adopted.

CI typically brings together blade-servers, enterprise storage arrays, storage area networks, IP networking, virtualization, and management software into a single product. CI means that multiple pre-engineered and pre-integrated components operate under a single controlled converged architecture with a single point of management and a single source for end-to-end support. CI provides a localized single resource pool that enables a higher overall resource utilization than with a legacy island-based infrastructure. Overall acquisition cost is lower and management is simplified. In the data center, CI typically has a smaller footprint with less cabling and can be deployed much faster than traditional infrastructure.

Design Trend Towards Software-Defined Data Centers (SDDCs)

Traditional data centers are hardware-centric. Emerging data centers are software-centric. While the concept is still evolving, a software-defined data center (SDDC) is a software-centric architectural approach based on virtualization and automation. To logically define all infrastructure services, the SDDC applies the widely successful principles of server virtualization

—abstraction, isolation, and pooling

—to the remaining network and storage infrastructure services. SDDC management is automated through policy-based software which controls both on-premises and off-premises resources. With SDDC, traditional enterprise applications can be supported in a more flexible and cost effective manner. SDDC represents the epitome of the agile digital business model, where pooled resources adapt and respond to shifting application requirements.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 1. SDDC

Virtualized servers are probably the most well-known software-defined IT entity, where hypervisors running on a cluster of hosts allocate hardware resources to virtual machines (VMs). In turn, VMs can function with a degree of autonomy from the underlying physical hardware. Software-defined storage (SDS) and software-defined networking (SDN) are based on a similar premise: physical resources are aggregated and dynamically allocated based on predefined policies with software abstracting control from the underlying hardware. The result is the logical pooling of compute, storage, and networking resources. Physical servers function as a pool of CPU resources hosting VMs, while network bandwidth is aggregated into logical resources, and pooled storage capacity is allocated by specified service levels for performance and durability.

Once the data center has abstracted resources, SDDC services make the data center remarkably adaptable and responsive to business demands. In addition to virtualized infrastructure, the SDDC includes automation, policy-based management, and hybrid cloud services. The policy-based model insulates users from the underlying commodity technology, and policies balance and coordinate resource delivery. Resources are allocated where needed, absorbing utilization spikes while maintaining consistent and predictable performance. Conceptually, SDDC encompasses more than the IT infrastructure itself; it also represents an essential departure from traditional methods of delivering and consuming IT resources. Infrastructure, platforms, and software have become services, and SDDC is the fundamental mechanism that underpins the most sophisticated cloud services. The most effective SDDC deployments are based on technology that provides simple implementation, administration, and management. This requires an infrastructure solution with an extremely high level of efficiency and serviceability, such as hyper-converged infrastructure.

Hyper-Converged Infrastructure

Hyper-converged infrastructure (HCI) is the next level of converged infrastructure. HCI is a new type of CI with a software-centric architecture based on smaller, best of breed industry-standard building-block servers that can be scaled. The server-based building blocks easily scale as requirements change. HCI has a software-defined architecture with everything virtualized. Compute, storage, and networking functions are decoupled from the underlying infrastructure and run on a common set of physical resources that are based on best of breed industry-standard components. Hyper-converged systems eliminate cost and complexity by eliminating the need for separate storage arrays and SAN components. Instead, they adopt best of breed industry-standard server platforms with local directattached storage (DAS), which is virtualized using software-defined storage technology. (See Figure 2 below.) By integrating these technologies, HCI systems are managed as a single system through a common toolset.

The ideal HCI solution integrates these building-block servers with simple and familiar management software for reliability, availability, and serviceability. This allows the use of top of the line, best of breed industry-standard x86 servers, eliminating the need for specialty hardware and reducing capital cost. Simple and familiar management software allows a common operational model, which drives efficiency and enables workload mobility, lowering operational costs. Flexible scalability, with nodes added to provide additional compute and storage resources, allows the environment to expand when needed to meet business demands.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 2. CI and HCI

HCI carries forward the benefits of CI, including a single shared resource pool, and takes them even further. By reinventing the underlying data architecture, HCI includes full data services. Complete integration and innovation at the software layer allows for radically simple end-to-end data management. Deploying new infrastructure, which could take days in the build-your-own model, can be up and running in under 30 minutes, because HCI offers automated discovery and integration. Ideally, HCI is fully integrated, preconfigured, and tested. This provides a simple, cost effective, non-disruptive scalable solution with centralized management functionality, rich data services, and a single source of support.

HCI enables faster, better, and simpler management of consolidated workloads, virtual desktops, business-critical applications, and remote office infrastructure.

HCI solutions have distinct features including scalability, simplicity, and data services.



Scalability.

Hyperconverged infrastructures are designed to scale out by adding nodes, which provides a predictable “pay-as-yougrow” approach. Adding nodes rather than separately adding CPUs or storage capacity, provides linear performance and an elastic infrastructure. Dynamic pooled resources are allocated according to fluctuating workload requirements. This absorbs application workload spikes and maintains performance consistency. Mid-sized IT departments or remote enterprise-edge locations, like branch offices, can implement an inexpensive, entry-level HCI solution, starting small and then easily and non-disruptively scaling both capacity and performance. HCI integration with public-cloud offerings can also seamlessly and securely expand capacity on demand and without limits to provide a hybrid-cloud solution.



Simplicity.

Hyper-convergence changes the game in terms of management and serviceability. Seamless integration among HCI elements unifies operations, using familiar consistent interfaces, and simplifies management. In addition, HCI facilitates simple workload mobility within the entire SDDC. The HCI management software stack includes applications for monitoring, logging, security and access control, compliance and upgrades, in addition to configuration utilities for virtual machines, network, and data services. The building-block design provides a superior implementation model in which all the components have been fully integrated, preconfigured, and tested, making the system simple to set up, expand, and maintain.



Data Services. HCI provides the same level of mission-critical data services provided by traditional high-end enterprise storage arrays. Enterprise IT applications are designed with the expectation that the IT infrastructure is equipped for consistent performance, high availability, and disaster recovery. HCI meets these expectations with rich data services such as deduplication, compression, replication, and backup and recovery. HCI brings consumption-based infrastructure economics and flexibility to enterprise IT without compromising on performance, reliability, or availability.

So when should CI be implemented and when is HCI a better option? The answer depends on the scale and scope of the infrastructure and the workloads. If the purpose is to support a large number of dense workloads and a multi-petabyte capacity, then CI is a better option. But for a smaller set of workloads

—including the most demanding loads like databases and OLTP, but at a smaller scale—then

HCI is an excellent option. It also is the appropriate choice for specific departments or remote offices. In short, HCI is ideal for applications that need agility and need to scale quickly at the lowest cost pe r unit. HCI is easy to deploy with little expertise. HCI doesn’t

VXRAIL CONCEPTS AND ARCHITECTURE

replace CI, but it allows IT to better tier infrastructure for varied application needs. Most IT operations can benefit from a combination of

CI and HCI that can flex to meet the evolving demands of their business.

In summary, IT organizations are rapidly evolving into cloud-centric business models where agility, scalability, security, resource optimization, and SLAs are paramount. The SDDC architecture makes the hybrid cloud possible by defining a platform common to both private and public clouds. Figure 3 below illustrates the three options for enterprises to establish an SDDC: 1) build their own; 2) use a converged infrastructure; or 3) use a hyper-converged infrastructure. With seamless integration of the technology stack, both CI and

HCI create platforms allow IT organizations to efficiently and effectively transition to a modern Software Defined Data Center (SDDC).

Of the three options, HCI is the fastest and easiest way to deploy a fully virtualized software-defined data center (SDDC) environment, allowing IT organizations to focus on innovation and adding business value.

Figure 3. One Destination, Multiple Deployment Approaches

VXRAIL CONCEPTS AND ARCHITECTURE

DELL EMC CONVERGED-INFRASTRUCTURE PLATFORMS OVERVIEW

This section reviews the CI and HCI platform architectures and product portfolios offered by Dell EMC and then specifically focuses on the VxRail Appliance. Included is an introduction to the VxRail architecture and components with a specific emphasis on the key integrated VMware software technologies that provide VxRail core services and functionality.

Dell EMC specializes in industry-leading converged and hyper-converged infrastructure platforms which simply and quickly transition data centers to a modern SDDC, enabling business transformation. Simplicity is the core driver behind the Dell EMC portfolio of CI platforms. The mission is to break down the silos of static infrastructure in the data center and make available flexible, shared pools of resources. With the Dell EMC portfolio, IT leaders have the flexibility to shift resources from maintaining infrastructure to delivering new, innovative business services while remaining cost-effective. These systems can quickly and reliably modernize the data center to meet th e evolving and dynamic demands of today’s tech-savvy business workforce.

The Vblock platform originated as a pioneering converged-infrastructure solution from VCE, bringing together VMware virtualization,

Cisco networking and compute, and EMC storage. The CI portfolio expanded quickly, offering increased choice, flexibility, and targeted application-workload solutions as new workload platforms emerged in the industry. Applications are now typically identified by industrydefined workload platforms: Platform 1.0 which refers to mainframe-application workloads; Platform 2.0, which refers to client-server and virtualized x86 traditional-application workloads; and Platform 3.0, which refers to Big Data applications with new workloads built for cloud, social and mobile. Figure 4 below illustrates the industry-defined IT platforms and enabling technologies.

Figure 4. Industry-Defined Workload Platforms

Figure 5 below illustrates the Dell EMC portfolio of converged and hyper-converged infrastructure solutions that feature pre-integrated, preconfigured components, tested, validated, and qualified with a single source of support. The portfolio is built on the widely adopted, industry-leading VMware technology for core functionality and management operations. The architectures are Blocks, Racks and

Appliances and the correlated design points are proven, flexible, and simple. Each architecture has its own distinct role in a SDDC and hybrid-cloud solution based on application workload and business requirements.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 5. Dell EMC Infrastructure-Solutions Portfolio

Block Architecture

In the Block architecture, Dell EMC offers two product families, Vblock and VxBlock. These systems bring together VMware virtualization, Cisco networking and compute, and varied Dell EMC storage arrays. The Block system architecture typically implements

Cisco UCS server blades configured as ESXi hosts for compute layer services. The VxBlock adds two fully integrated options for software-defined networking (SDN) and network-layer abstraction, VMware NSX techno logy or Cisco’s Application Centric

Infrastructure (ACI). Within the Vblock product family, specific models correspond to specific data-center purposes, but they all focus on traditional, mission-critical enterprise workloads.



The Block architecture desig n center is “proven.” Vblock and VxBlock are proven and widely deployed. In fact, they have become an industrystandard CI system with the terms “Vblock” and “converged infrastructure” often used interchangeably.



The Block system-level architecture has disaggregated compute, memory, network, and storage which allows for variation at all layers. Vblock and VxBlock also have the traditional elements required to deliver legacy persistence and networking capabilities.

This Block system-level architecture has step-function scaling.



The Block architecture workload and business requirements focus on rich infrastructure services to support Platform 2.0 applications.

Vblock and VxBlock both support any open-system workload in the data center and have a broad set of traditional data services to meet enterprise business requirements.

Rack Architecture

The VxRack expands Dell EMC

’s industry-leading CI portfolio to include hyper-converged infrastructure. The VxRack architecture scales linearly with hyper-converged node servers that consolidate compute and storage layers. It incorporates a leaf-spine network architecture specifically designed to accommodate extensive, scale-out workloads and over a thousand nodes. Dell EMC refers to the

VxRack platform as hyper-convergence at rack scale. It represents a full system deployment that includes integrated storage-attached servers and network hardware. The VxRack implements VMware Cloud Foundation to facilitate ESXi server-based software-defined storage and to deploy a virtualized NSX network layer over the physical network fabric for SDN. VxRack provides performance, reliability, and operational simplicity at large scale.



The Rack archite cture center is “flexible.” The VxRack is an example of the flexible design center. It’s an adaptable platform in terms of its hardware and persona. (Persona flexibility refers to the VxRack ability to run multiple hypervisors

—ESXi or KVM—as well as support bare-metal deployments.)



Rack systems are engineered systems with network design as the key differentiator. At scale, leaf-and-spine and top-of-rack (ToR) cabling architectures are critical. Rack architecture incorporates the leaf-and-spine network and ToR cabling architectures that

VXRAIL CONCEPTS AND ARCHITECTURE

enable scaling to hundreds and thousands of nodes, deployed not in small clusters but as a massive, rack-scale, web-scale, and hyper-scale system. VxRack incorporates the network fabric as a core part of the system design and management stack. The network is not just bundled but rather is an integral part of the system with single support and warranty plus management integration.

Rack system-level architecture uses software-defined storage (SDS) and best of breed industry-standard x86 hardware. This rack system-level architecture has linear-function scaling.



Rack-architecture workload and business requirements focus on flexibility for different workload types (Platform 2.0, Platform 3.0, kernel-mode VMs, Linux containers) and come in multiple personas. (VxRack supports OpenStack and VMware hypervisors initially and will support others in the future).

Appliance Architecture

The hyper-converged VxRail Appliance features a clustered node architecture that consolidates compute, storage, and management into a single, resilient, network-ready HCI unit. The software-defined architectural structure converges server and storage resources, allowing a scale-out, building-block approach, and each appliance carries management as an integral component. From a hardware perspective, the VxRail node is a server with integrated direct-attached storage. No external network components are included with the appliance; VxRail leaves that up to the customer (although VCE can bundle switch hardware and NSX can function as an integrated option for SDN). This allows the VxRack to seamlessly integrate into the existing network infrastructure, preserving existing investment in network infrastructure, processes, and training.

Organizations benefit from the simplicity of the appliance architecture that expedites application deployment while providing the same data services expected from high-end systems.



The Appliance architecture design center is “simple.” VxRail is simple to acquire, deploy, operate, scale, and maintain.



The Appliance system-level architecture uses SDS and multi-node servers with integrated storage and can leverage whatever network infrastructure is available. Appliance architecture provides low-cost and low-capacity entry points with simple configurations that can easily scale.



Appliance-architecture workload and business requirements focus on simplicity and the ability to start small and grow easily. VDI and productivity applications are examples of the initial workloads deployed in appliances.

Figure 6. Dell EMC Blocks, Racks, and Appliances

All three Dell EMC converged infrastructure architecture models are often deployed in the same data center or, as shown below in the

Figure 7 below, can be part of a Federated Enterprise Hybrid Cloud (FEHC) that allows integration of the entire suite of data center solutions (including those in remote, branch and edge locations) and provisioning of the resources in local or remote sites using a common service catalog.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 7. Dell EMC Converged Infrastructure in the Enterprise Data Center

VxRail Product Profile

VxRail was jointly developed by Dell EMC and VMware and is the only fully integrated, preconfigured, and tested HCI appliance powered by VMware Virtual SAN (vSAN). Managed through the ubiquitous VMware vCenter Server interface, VxRail provides a familiar vSphere experience that enables streamlined deployment and the ability to extend the use of existing IT tools and processes. The

VxRail Appliance is fully loaded with integrated, mission-critical data services from Dell EMC and VMware including compression, deduplication, replication, and backup. The VxRail Appliance delivers resiliency and centralized-management functionality enabling faster, better, and simpler management of consolidated workloads, virtual desktops, business-critical applications, and remote-office infrastructure. As the exclusive hyper-converged infrastructure appliance from Dell EMC and VMware, VxRail is the easiest and fastest way to stand up a fully virtualized SDDC environment.

VxRail provides an entry point to the SDDC, catering to small- and medium-sized environments, remote and branch offices (ROBO), and edge departments, as well as providing agility for pressing IT initiatives within larger data centers. Small-shop IT personnel benefit from the simplicity of the appliance model to expedite the application-deployment process while still taking advantage of data services only typically available in high-end systems. Larger data centers benefit by rapid deployment where a complete vSphere environment can be installed and be ready to deploy applications within few hours of the system arriving on site. VxRail allows businesses to start small and scale non-disruptively. Storage is configured to meet appropriate application capacity and performance requirements. In addition, nodes are available with different compute power, memory, and cache configurations to closely match the requirements of new and expanding use cases. As requirements grow, the system easily scales out and scales up in granular increments. Finally, because the VxRail is jointly engineered, integrated, and tested, organizations can leverage a single source of support and remote services from Dell EMC.

VxRail environments are configured as a cluster consisting of a minimum of three server nodes, with each node containing internal storage drives. VxRail systems are delivered with the software loaded and ready to attach to a customer provided network. While most environments use 10Gb Ethernet for internal and external communications, 1Gb Ethernet connectivity is also available. Using a simple wizard, the system can be configured to match unique site and networking requirements.

The VxRail software layer uses VMware technology for server virtualization, network virtualization, and software-defined storage.

VxRail nodes are configured as ESXi hosts, and VMs and services communicate using the virtual switches for logical networking.

VMware vSAN technology pools storage resources and is implemented at the ESXi-kernel level. This highly efficient SDS layer consumes minimal system resources, making more resources available to support user workloads. The kernel-level integration also dramatically reduces the complexities involved in infrastructure management. vSAN presents a familiar datastore to the nodes in the cluster and Storage Policy Based Management provides the flexibility to easily configure the appropriate level of service for each VM.

VXRAIL CONCEPTS AND ARCHITECTURE

The VxRail management platform is a strategic advantage for VxRail and further reduces operational complexity. VxRail Manager presents a simple dashboard interface for infrastructure monitoring and automation of management tasks such as software upgrades.

Since VxRail nodes function as ESXi hosts, vCenter Server is used for VM-related management, automation, monitoring, and security. vSphere is a well-established virtualization platform

—a familiar usable entity in most data centers. All three Dell EMC infrastructure solutions

—Vblock/VxBlock, VxRack, and VxRail—leverage vSphere for ESXi-based virtualization and VM networking, and support a common set of VMware and Dell EMC services. This enables a VxRail implementation to integrate smoothly into VMware-centric data centers and to operate in concert with Block and Rack deployments. NSX for SDN can also be easily integrated into the solution as an option. This allows all datacenter assets to be maintained using a single administrative platform. Hence, monitoring, upgrading, and diagnostics activities are performed efficiently and reliably. Blocks, Racks, and Appliances use the same migration technologies from

VMware for moving VMs and data, thus providing advantages in workload mobility. Other familiar services available on VxRail include

RecoverPoint replication, Data Domain for backup, Dell EMC Remote Secure Services (ESRS) and cloud tiering services. VxRail also has optional support for VCE Vision Intelligent Operations software, allowing IT shops to leverage integration with VxRack and Vblock, enabling them to deliver a full enterprise solution for all workloads and to replicate and protect from the enterprise edge to the data center.

To summarize, VxRail creates IT certainty. It is built on the enterprise-proven VMware hypervisor, vSAN technology, management, and ecosystem that removes complexity and simplifies day-to-day operations. The system architecture is designed to predictably evolve with the business. The system scales by deploying preloaded appliances to effortlessly extend the environment, rather than by building and manually integrating servers. VxRail, powered by vSAN and featuring Dell PowerEdge Servers, continues to evolve so business can thrive without worrying about the IT infrastructure.

VXRAIL CONCEPTS AND ARCHITECTURE

VXRAIL HARDWARE ARCHITECTURE

The Dell EMC VxRail Appliance family, powered by vSAN, is the new standard in hyper-converged, providing extreme flexibility to granularly add capacity and performance on demand and enabling customers to easily extend use cases across the virtualized environment. The appliance-based design allows IT centers to scale capacity and performance non-disruptively, so they can start small and grow incrementally with minimal up-front planning. VxRail environments can be designed to support a small number of virtual machines (VMs) and scale to thousands. The VxRail architecture enables a predictable pay-as-you-grow approach that aligns to changing business goals and user demand. Dell EMC and VMware are continuously innovating, and VxRail 4.0 has enhanced the

VxRail portfolio with new Dell PowerEdge-based models that offer extreme configuration flexibility. This flexibility allows customers to choose performance, graphics, and capacity as required for VMware environments, and it supports more use cases. In addition, the proven 2U, 4-node VxRail models have also been updated with more powerful Broadwell, E5 v4 processors.

The Dell EMC VxRail Appliance product portfolio offers a range of platforms:



G Series

—general-purpose configurations, ideal for widely deployed general purpose applications and VDI workloads



E Series

—cost-optimized entry point for remote office branch office (ROBO) deployments with support for smaller and lower cost nodes deployed in 3node clusters, but also with the option for relatively high storage capacity (for users who don’t delete any of their files)



P Series

—performance optimized for high-end use cases with business critical, performance intensive applications and/or inmemory databases



V Series

—VDI optimized for specialized use cases with graphics intensive applications such as high-end 2D/3D visualization applications, and is the only series that supports GPU cards



S Series

—storage dense configurations targeted at specialized use cases which require higher storage capacity at the server level such as big data & analytics or collaboration applications

The VxRail Appliance is built using a distributed-cluster architecture consisting of modular blocks that scale linearly as the system grows from as small as three nodes to as large as 64 nodes. Nodes are available with different form factors, including: a 2U, four-node appliance for dense compute requirements; single-node appliances for other use cases, including entry-level systems; performance optimized; VDI optimized with GPU; and storage-optimized configurations supporting high-capacity HDD drives. Extensive compute, memory, and storage options are designed to fit multiple use cases. Customers may choose from a range of next-gen Intel processors, variable memory sizes, storage, and cache capacity to provide the right balance of compute, memory, and storage. Single-node scaling and a low-cost entry point let customers procure just the right amount of storage and compute for today’s requirements and effortlessly scale to accommodate tomorrow’s growth. Systems are available with all-flash storage configurations that deliver the industry’s most powerful HCI for applications that demand maximum performance and low latency.

Figure 8 below shows a VxRail model G Series Appliance, a four-node appliance with storage in front and compute in the back. This model is offered for general-purpose use cases with dense packaging. Both hybrid and all-flash storage configurations are available.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 8. VxRail G Series Four-Node Appliance

Single-node VxRail Appliance configurations are also available. Figure 9 below shows a P Series VxRail Appliance, a single-node appliance. This model is based on the Dell PowerEdge R730 server and, with expanded compute options, larger memory, and greater storage capacity, it enables new and more demanding use cases. It’s also available with hybrid and all-flash storage. This is a new offering with VxRail 4.0 along with other new appliances based on Dell PowerEdge servers. The V Series, based on a hardened Dell

PowerEdge R730, is optimized for VDI applications with optional GPU processors. The E Series, based on the Dell PowerEdge R630, is an entry-cost model option that is ideal for smaller environments such as ROBO. There is also the S Series, based on the Dell

PowerEdge R730XD, which is a storage-dense configuration that supports even greater hybrid capacity for data-intensive applications.

Figure 9. VxRail P Series Single-Node Appliance

VxRail Appliance Cluster

VxRail nodes are enclosed in either a one-node or four-node appliance depending on the model. Each node includes one or two multicore processors and six, ten, fourteen, or sixteen disk drives, either all-flash SSDs or a hybrid mix of flash SSDs and HDDs. The nodes form a networked cluster with a minimum of 3 nodes (introduced with VxRail 4.0) and a maximum of 64. Nodes within a cluster must be of the same storage configuration, either all hybrid or all flash. The flexibility to mix nodes within a cluster is supported, however the first four nodes must have the same compute, memory, and storage configuration, and mixing of 1GbE and 10GbE is not supported.

From the minimum configuration to the maximum, the VxRail cluster is easily expanded one node at a time.

VxRail Node

The VxRail Appliance is assembled with proven server-node hardware that has been integrated, tested, and validated as a complete solution by Dell EMC. The current generation of VxRail nodes all use Broadwell-based Intel Xeon E5-2600 V4 processors. The Intel

Xeon E5 processor family is a multi-threaded, multi-core CPU designed to handle diverse workloads for cloud services, highperformance computing, and networking. The number of cores and memory capacity differ for each VxRail Appliance model. Figure 10 below shows a physical view of a node server with its processors, memory and supporting components. All VxRail models have similar components but may be laid out differently physically.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 10. VxRail G Series Physical Node

Each node server includes the following technology:



1 or 2 Intel Xeon E5-2600 V4 processors with up to 22 cores per processor



Up to 24 DDR4 DIMMs, providing memory capacity ranging from 64GB to 1536GB per node, depending on model



A PCIe SAS disk-drive controller supporting 12GB SAS speeds



A 64GB SATADOM used to boot ESXi on the node



Single Dual-port 10GbE or four-port 1Gbe network adapters for the G Series models, and one Network Daughter Card with (2)

10GbE + (2) 1GbE ports for other models



An integrated graphics BMC port, 2 USB ports, 1 Serial port, 1 VGA port. Single-node appliances support iDRAC and not the BMC port.

Figure 11 below shows a single G Series (10GbE) node from the back. The Series is a dense configuration with four nodes in each appliance.

Figure 11. VxRail G Series Node Serves with 10GbE ports: Back View

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 12 shows the back of a P Series; a single-node appliance. All single-node appliances have a similar physical layout.

Figure 12. VxRail P Series Node Server: Back View

VxRail Node Storage Disk Drives

Storage capacity for the VxRail Appliance is provided by disk drives that have been integrated, tested, and validated by Dell EMC

. 2.5” form-factor Solid State Disks (SDD) and mechanical Hard Disk Drives (HDD) are used. A configuration the uses

3.5” form-factor drives is also available for dense storage requirements. Disks drives are logically organized into disk groups. Disk groups are configured in two ways:



Hybrid configurations, which contain a single SDD flash-based disk for caching (the caching-tier) and multiple HDD disks for capacity

(the capacity-tier)



All-flash configurations, which contain all SDD flash drives for both cache and capacity

The flash drives used for caching and capacity have different endurance levels. Endurance level refers to the number of times that an entire flash disk can be written every day for a five-year period before it has to be replaced. A higher-endurance SSD is used for write caching and capacity optimized SSDs are used for the capacity tier. Currently, the caching tier uses 200GB, 400GB, 800GB, and

1600GB flash disks, and the capacity tier uses either 1.92 or 3.84TB flash SSDs, 1.2TB HDDs, 2TB HDDs, and 4TB (3.5” form-factor).

All VxRail disk configurations use a carefully designed cache-to-capacity ratio to ensure consistent performance.

VxRail Networking

The VxRail Appliance is a self-contained environment with compute, storage, server virtualization and management services that make up a hyper-converged infrastructure. The distributed cluster architecture allows independent nodes to work together as a single system.

Each node both contributes to and consumes system resources. This close coupling between nodes is accomplished through IP networking connectivity. IP networking also provides access to virtual machines and the services they provide.

While VxRail is a self-contained infrastructure, it is not a stand-alone environment, and i t’s intended to connect and integrate with the customer

’s existing datacenter network. A typical implementation uses one or more customer-provided 10GbE Top of Rack (ToR) switches to connect each node in the VxRail cluster. For smaller environments, an option to use 1GbE switches is available, but these lower bandwidth networks limit performance and scale. While the network switches are typically customer provided, Dell EMC offers

Connectrix VDX 6740 Ethernet switches which can be included with the system. Figure 13 below shows typical network connectivity using two switches for redundancy. Single switch implementations are also supported.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 13. Typical VxRail Physical Network Connectivity

The number of Ethernet switch ports required depends on the VxRail model and whether it is configured as a hybrid storage configuration or as all flash. The all-flash system requires two 10GbE ports and hybrid systems use either two 10GbE ports per node or four 1GbE ports per node. The single-node appliances have an embedded four-port NIC with two (2) 10GbE ports and two (2) 1GbE ports. For 1GbE networks, the 10GbE ports auto-negotiate down to 1GbE and for 10GbE networks the (2) 1GbE ports are not configured by default. Optionally on the single-node appliances, a second PCIe NIC can be added, also with two (2) 10GbE ports. NIC ports use either RJ45 or SPF+ connections. The second PCIe NIC is not configured by VxRail management, but can be used by the customer to support non-VxRail traffic, primarily VM traffic. The additional ports are managed through vCenter.

Network traffic is segregated using switch-based VLAN technology and vSphere Network IO Control. Four types of network traffic exist in a VxRail cluster:



Management. Management traffic is use for connecting to VMware vCenter Web Client, VxRail Manager, and other management interfaces and for communications between the management components and the ESXi nodes in the cluster. Either the default

VLAN or a specific management VLAN is used for management traffic.



vSAN. Data access for read and write activity as well as for optimization and data rebuild is performed over the vSAN network. Low network latency is critical for this traffic and a specific VLAN is required to isolate this traffic.



vMotion. vMotion is a vSphere feature that allows virtual machines mobility between nodes. A separate VLAN is used to isolate this traffic.



Virtual Machine. Users access virtual machines and the service provided over the VM network(s). At least one VM VLAN is configured when the system is initially configured and others may be defined as required.

VXRAIL CONCEPTS AND ARCHITECTURE

Pre-installation planning includes verifying that enough physical switch ports are available and that the ports are configured for the appropriate VLANs. VLANs along with IP address and other network configuration information are used when the system is configured at the time of installation. Detailed planning and configuration information is included in the VCE VxRail Network Guide.

When the system is initialized at the time of installation, the wizard automatically configures the required uplinks following VxRail standards and best practices. The configuration wizard asks for the NIC configuration and accepts two options:



4X1GbE. This is only valid for systems with hybrid storage configuration. If the node physically has two (2) 10GbE ports and two (2)

1GbE ports, the 10GbE is negotiated down to 1GbE. Management, vSAN, vMotion, and VM traffic is associated with these ports with the appropriate Network teaming policy and NIOC settings.



2X10GbE. Management, vSAN, vMotion, and VM traffic is associated with these ports with the appropriate Network teaming policy and NIOC settings.

If nodes have additional physical NIC ports, they can be configured after installation using standard vSphere procedures.

1GbE Network Option

The Ethernet network not only provides connectivity to the VMs and services, it also provides the backplane for the nodes in a hyperconverged infrastructure to aggregate and share system resources. Therefore network bandwidth is critical to system scale and performance. Today, most datacenters are built with 10Gb Ethernet connectivity, but 1GbE still exists in many environments. To support these environments, Dell EMC also offers 1GbE VxRail models for smaller less demanding workloads. The following are considerations for using the 1GbE connectivity option.



1GbE is only supported for hybrid storage configurations as it does not provide the bandwidth necessary for the ultra-high performance required by an all-flash system.



The maximum supported node count is eight nodes per cluster, because vSAN traffic increases with the number of nodes.



Only nodes with single socket CPUs are supported



A minimum of four NICs are required per node. This increases the number of switch ports required.

VxRail Models and Specifications

VxRail Appliance models are available to meet the requirements of a wide set of use cases. For general purpose use cases, there is the compute dense four-node appliance configuration. For smaller workloads, an entry-level system using single-node appliances start as small as three nodes. A performance-optimized and a VDI-optimized configuration is available in both all-flash and hybrid configurations. For use cases requiring even greater storage, a hybrid storage-dense configuration that uses larger capacity 3.5 inch drives is available. All models have a wide range of available CPU, memory, SSD cache, and capacity storage configuration options.

Figure 14 illustrates the range of platforms designed to support multiple use cases.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 14. Configuration for Wide Range of Use Cases

Figure 15 shows the high-level specs for the five VxRail series.

Figure 15. VxRail Series High Level Specs

The densest compute configuration is the G Series with four nodes per appliance. This model uses the proven 2U 4-nodes design point, and is now upgraded to the more powerful Broadwell, E5 V4 processors. All other configurations are single-node appliances based on Dell PowerEdge server technology, the number-one selling X86 server platform, with greater storage capacity, larger memory, and more powerful CPU options. The E Series is intended as an entry-level system and is ideally suited for ROBO. The P

Series is performance optimized with more powerful processor options, memory configurations up to 1536GB per node, and large storage capacity. The V Series is optimized for VDI environments that require high-end 2D and 3D graphic processing. It supports one or two Graphic Processing Units (GPUs) per node. The supported GPUs are currently NVIDIA (Tesla M60) or AMD FirePro

(7150/7150X2. The S Series is offered as a hybrid configuration and is ideally suited for applications that require large storage applications such as collaboration and data analytics. All appliance models support either 10GbE or 1GbE network, however, 10Gb

Ethernet networks are required for all-flash configurations and environments that will scale greater than 8 nodes. The additional ports are available on the single node appliances and allow the customer to segregate VM network traffic.

Figure 16 below shows the different appliance form factors and refers to the rack space they consume in Rack Units (RU). A Rack Unit is 1.75 inches (44.45 mm). Appliances are installed in customer provided racks and a typical rack has a total capacity of 43 RU.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 16. Appliance Form Factor

VxRail Scaling

Current VxRail 4.0 configurations start with as few as three nodes and can grow in one-node increments up to 64 nodes, providing performance and capacity to meet a wide range of use cases. New appliances can be added non-disruptively and different model appliances can be mixed within a VxRail cluster. Flexible storage options also allow a node to start with a few drives and add drives as capacity requirements grow. Single nodes and drive scalability protect an optimized initial investment by allowing customers to start with what they need and expand the VxRail cluster by adding nodes and/or drives to increase performance and capacity as needed.

Consult your Dell EMC representative for assistance.

Figure 17. VxRail scaling from tens to thousands of VMs

VXRAIL CONCEPTS AND ARCHITECTURE

A few basic rules regarding scaling are worth considering for planning:

1. Balance: a. The first four nodes in a cluster must be the same processor and drive configuration (yes, VxRail can start with 3 nodes) b. All nodes must be running the same version of software c. All nodes in a chassis must be identical (applies to G Series)

2. Flexibility: a. Appliances in a cluster can be different models or series and can have different numbers of nodes b. Vary number of drives, CPU, memory, and model types in a cluster c. G Series appliances can be partially populated (balance rules must still be met)



Exceptions: o

Hybrid models and flash models cannot be mixed in a cluster o

Models that use 1GbE cannot be mixed with 10GbE networking models

VXRAIL CONCEPTS AND ARCHITECTURE

VXRAIL SOFTWARE ARCHITECTURE

The prior section introduced the flexible VxRail hardware architecture based on proven server technology . While the VxRail hardware helps differentiate the VxRail from other HCI solutions, VxRail is a complete appliance that includes software that enables a software defined data center. These sections on software architecture provide a comprehensive examination of all the VxRail software components and their relationships and co-dependencies. The VxRail Appliance is architected with software for appliance management, virtualization, and VM management. The software stack comes preinstalled and simply requires running a configuration wizard on site to integrate the appliance into an existing network environment. The VxRail management, operations, and automation software includes:



VxRail Manager

The VMware virtualization and virtual-infrastructure management software includes:



VMware vCenter Server



vSphere ESXi



vSAN (software-defined storage)



VMware vRealize Log Insight

Additional included Dell EMC Software



Recover Point for VMware

—15 VM licenses per G Series appliance chassis; 5 VM licenses per node for single node per chassis models



CloudArray

—1TB local/10TB Cloud-capacity license per chassis (all model types)

VxRail provides a unique and tightly integrated architecture for VMware environments. VxRail deeply integrates VMware virtualization software. Specifically, VMware vSAN is integrated at the kernel level and is managed with VMware vSphere, which enables higher performance for the VxRail Appliance as well as automated scaling and wizard-based upgrades.

The next sections review the VxRail management, operations, and automation software in depth.

Appliance Management

The introduction section of this TechBook addresses the complexity of the software-defined data center and the challenges of managing and maintaining an SDDC environment, and VxRail Manager responds to this challenge directly. In addition, VxRail

Appliance sites can take advantage of Vision Intelligent Operations for added management functionality within Dell EMC data centers.

VxRail Manager

VxRail Manager features a user-friendly dashboard for automating VxRail deployment and configuration and monitoring the health of individual appliances and individual nodes in the entire cluster. The VxRail Manager is preinstalled on the VxRail appliance as a single virtual machine and it can be accessed by pointing a browser at the VxRail Manager IP address or the DNS host name.

VxRail Manager dashboard displays storage, CPU, and memory utilization at the cluster, appliance, or individual node level. It also incorporates functionality for hardware serviceability and appliance platform life-cycle management. For instance, it guides systems administrators through adding new appliances to an existing cluster, and it automatically detects new appliances when they come online. VxRail Manager is also used to replace failed disk drives without disrupting availability, to generate and download diagnostic log bundles, and to apply VMware updates or software patches non-disruptively across VxRail nodes.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 18. VxRail Manager Main Dashboard

The VxRail Manager main dashboard displays the current status of overall system health. From there, administrators can access additional real-time system health details for both logical and physical resources and can view and analyze resource operability, performance, and utilization data.

Figure 19. The VxRail Manager Health Tab for Logical Resources

VxRail also leverages VMware vRealize Log Insight to monitor system events and provide ongoing holistic notifications about the state of virtual environment and appliance hardware. It delivers real-time automated log management for the VxRail Appliance with log monitoring, intelligent grouping, and analytics to provide better troubleshooting at scale across VxRail physical, virtual, and cloud environments. Furthermore, the VxRail Manager simplifies appliance platform life-cycle management by delivering patch software and update notifications that can be automatically installed without interruption or downtime.

Dell EMC Software Remote Services (ESRS), also accessible from within the VxRail Manager, provide enterprise-class support and services. ESRS includes online chat support and Dell EMC field-service assistance (as seen in Figure 21 below). In addition to ESRSspecific support, the VxRail Manager Support tab links to VxRail Community pages for things like Dell EMC Knowledgebase articles and user forums for FAQ information and VxRail best practices. Figure 20 below summarizes its details.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 20. VxRail Manager ESRS Details

Figure 21. The VxRail Manager Support Tab

Furthermore, the VxRail Manager provides access to a digital market for finding and downloading qualified software packages such as

CloudArray, VMware Horizon Air Hybrid-Mode, Data Domain Virtual Edition, RecoverPoint for VMs, and vSphere Data Protection.

Vision Intelligent Operations

Vision Intelligent Operations provides health and life-cycle management for Dell EMC converged-infrastructure environments. It performs multi-system and component discovery and identification, workload and system health monitoring, system optimization, as well as compliance management for security and system software. Vision maintains a holistic approach to converged, multi-system enterprise management, and it streamlines operations across a range of datacenter assets.

IT shops that are part of a broader Dell EMC-centric infrastructure may opt to purchase Vision software with their VxRail deployments.

VxRail Appliances are visible to and included in the Vision discovery process, so they can participate in an enterprise-wide, core-toedge Dell EMC management ecosystem.

VMware vSphere

The VMware vSphere software suite delivers an industry-leading virtualization platform to provide application virtualization within a highly available, resilient, efficient on-demand infrastructure

—making it the ideal software foundation for VxRail Appliances. ESXi and vCenter are components of the vSphere software suite. ESXi is a hypervisor installed directly onto a physical VxRail server node,

VXRAIL CONCEPTS AND ARCHITECTURE

enabling it to be partitioned into multiple logical servers referred to as virtual machines (VMs). VMs are configured on top of the ESXi server. VMware vCenter server is a centralized management application that is used to manage the ESXi hosts and VMs.

The following sections provide an in-depth examination of the VMware software components as implemented in the VxRail software architecture.

VMware vCenter Server

vCenter Server is the centralized platform for managing a VMware environment. VxRail includes a license to run vCenter hosted on

VxRail (the license is not transferrable to run vCenter on an external server). It is the primary point of management for both server virtualization and vSAN, and is the enabling technology for advanced capabilities such as vMotion, DRS and HA. vCenter scales to enterprise levels where a single vCenter can support up to 1000 hosts (VxRail nodes) and 10,000 virtual machines. vCenter supports a logical hierarchy of datacenters, clusters, and hosts, which allow resources to be segregated by use cases or lines of business and allows resources to move dynamically as needed. This is all done from a single interface.

As part of a VxRail deployment, a standalone vCenter instance is optionally configured on VxRail and provides the primary point of management for both the virtual machine and vSAN environments. The vCenter instance will be configured with an external Platform

Services Controller (PSC), where the vCenter server and the PSC are configured as separate virtual machines.

Figure 22 below is an example of three separate vCenter environments. The Vblock and two VxRail environments are managed as separate entities. This is a simple environment and in some cases the planning and deployment may be easier as there are no interactions.

Figure 22. Three Separate vCenter Environments

Beginning with release 3.5, a VxRail Appliance can optionally join an existing externally hosted vCenter Server 6.0 environment during the initial configuration. This allows for a central vCenter Server to manage multiple VxRail Appliances from a single pane of glass.

Each VxRail cluster appears within vCenter.

Figure 23 below shows an example where multiple VxRail clusters are part of an existing vCenter environment. Each VxRail is a unique and independent vSAN data store within vCenter.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 23. VxRail within an Existing vCenter Environment

The external vCenter server can be a physical server or a virtual server running as either a VCSA or in a Windows virtual machine. The

Platform Services Controller (PSC) can be either embedded or non-embedded. As part of the initial configuration, the management page of the VxRail Wizard presents the option to join an existing vCenter. If selected, specify the hostname of the vCenter Server and administrator password, identify the datacenter to add the VxRail environment, and supply the name of the cluster. Figure 24 below shows an example of the VxRail Initialization Wizard dialog to specify joining an existing vCenter Server.

Figure 24. Initialization Wizard

The datacenter must already exist within vCenter, and the cluster will be created as part of the installation process. Please consult Dell

EMC sales or support representatives for more details regarding initial configuration requirements.

vCenter Services and Interfaces

vCenter provides a number of services and interfaces, including:



Core VM and resource services such as an inventory service, task scheduling, statistics logging, alarm and event management, and

VM provisioning and configuration



Distributed services such as vSphere vMotion, vSphere DRS, and vSphere HA



vCenter Server database interface

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 25. vCenter Services

PSC Deployment Options

The Platform Services Controller (PSC) can be deployed as either embedded (in externally hosted vCenter) or external (in VxRail hosted vCenter or externally hosted vCenter), as depicted in Figure 26.



Embedded PSC is ideal for small environments, or if simplicity and reduced resource utilization are key factors for the environment.

The vCenter Server is bundled with an embedded PSC, and all the PSC services reside on the same host machine as vCenter

Server.



External PSC is ideal for larger environments, where there are multiple vCenter servers, but you want a single pane-of-glass for the site. The services bundled with the Platform Services Controller and vCenter Server are deployed on different virtual machines or even different physical servers. When utilizing an externally hosted vCenter with the external PSC Enhanced Linked Mode (ELM) is supported.

Figure 26. Embedded and External PCS Deployments

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 27. External PSCs Configured for High Availability

Enhanced Linked Mode

As shown in figures 27 and 28 above, multiple vCenter Servers can connect to the same external Platform Service Controller.

Enhanced Linked Mode enables consolidated management view of multiple vCenter Servers configured to use the Platform Services

Controller domain. This includes a common inventory where an administrator can search for objects across vCenter Servers. Roles, permissions, licenses, and other key data across systems are also replicated across vCenter instances.

This single-pane-of-glass view provides enterprise level scale and works particularly well in large multiple VxRail cluster environments or when the VxRail appliance joins an existing large vSphere environment. In addition, Enhanced Link Mode also enables capabilities such as Cross vCenter vMotion where VMs can be moved between vCenter.

Enhanced Linked Mode is supported with VxRail when running an externally hosted vCenter with VxRail and utilizing external PSC.

VMware vSphere ESXi

vSphere is the core operational software in the VxRail Appliance. vSphere aggregates a comprehensive set of features that efficiently pools and manages the resources available under the ESXi hosts. Keep in mind that this TechBook focuses on vSphere technology specifically as it pertains to the VxRail Appliance. Features included in other vSphere implementations may not apply to VxRail and features included in VxRail may not apply to other implementations.

ESXi Overview

VMware ESXi is an enterprise-class hypervisor that deploys and services virtual machines. Diagram 25 illustrates its basic architecture.

ESXi partitions a physical server into multiple secure and portable VMs that can run side by side on the same physical server. Each VM represents a complete system

—with processors, memory, networking, storage, and BIOS—so any operating system (guest OS) and software applications can be installed and run in the virtual machine without any modification. The hypervisor provides physicalhardware resources dynamically to virtual machines (VMs) as needed to support the operation of the VMs. The hypervisor enables virtual machines to operate with a degree of independence from the underlying physical hardware. For example, a virtual machine can be moved from one physical host to another.

Also, the VM’s virtual disks can be moved from one type of storage to another without affecting the functioning of the virtual machine. ESXi also isolates VMs from one another, so when a guest operating system running in one VM fails, other VMs on the same physical host are unaffected and continue to run. Virtual machines share access to CPUs and the hypervisor is responsible for CPU scheduling. In addition, ESXi assigns VMs a region of usable memory and provides shared access to the physical network cards and disk controllers associated with the physical host. Different virtual machines can run different operating systems and applications on the same physical computer.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 28. Birds-Eye View: vSphere ESXi Architecture

Communication between vCenter Server and ESXi Hosts

vCenter Server communicates with the ESXi host through a vCenter Server agent, also referred to as vpxa or the vmware-vpxa service, which is started on the ESXi host when it is added to the vCenter Server inventory. (See Figure 29.) Specifically, the vCenter vpxd daemon communicates through the vpxa to the ESXi host daemon known as the hostd process. The vpxa process acts as an intermediary between the vpxd process that runs on vCenter Server and the hostd process that runs on the ESXi host, relaying the tasks to perform on the host. The hostd process runs directly on the ESXi host and is responsible for managing most of the operations on the ESXi host including creating VMs, migrating VMs, and powering on VMs.

Figure 29. Communication Between vCenter and ESXi Hosts

Virtual Machines

A virtual machine consists of a core set of the following related files, or a set of objects. (See Figure 30.) Except for the log files, the name of each file starts with the virtual machine’s name (VM_name). These files include:



A configuration file (.vmx) and/or a virtual-machine template-configuration file (.vmtx)



One or more virtual disk files (.vmdk)



A file containing the virtual machine’s BIOS settings (.nvram)



A virtual machine’s current log file (.log) and a set of files used to archive old log entries (-#.log)

VXRAIL CONCEPTS AND ARCHITECTURE



Swap files (.vswp), used to reclaim memory during periods of contention



A snapshot description file (.vmsd), which is empty if the virtual machine has no snapshots

Figure 30. Virtual Machine Files

Virtual Machine Hardware

A virtual machine uses virtual hardware. Each guest operating system sees ordinary hardware devices and does not know that these devices are virtual. (Hardware resources are shown below in Figure 31.) All virtual machines have uniform hardware, except for a few variations that the system administrator can apply. Uniform hardware makes virtual machines portable across VMware virtualization platforms. vSphere supports many of the latest CPU features, including virtual CPU performance counters. It is possible to add virtual hard disks and NICs, and configure virtual hardware, such as CD/DVD drives, floppy drives, SCSI devices, USB devices, and up to 16

PCI vSphere DirectPath I/O devices.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 31. Hardware Resources for VMs

Virtual Machine Communication

The Virtual Machine Communication Interface (VMCI) provides a high-speed communication channel between a virtual machine and the hypervisor. VMCI devices cannot be added or removed. The SATA controller provides access to virtual disks and DVD/CD-ROM devices. The SATA virtual controller appears to a virtual machine as an AHCI SATA controller. Without VMCI, virtual machines would communicate with the host using the network layer, which adds overhead to the communication. With VMCI, communication overhead is minimal, and tasks requiring that communication can be optimized. An internal network can transmit an average of slightly over

2Gbps using VMXNET3. VMCI can go up to nearly 10Gbps with twelve 8k-sized queue pairs.

VMCI provides socket APIs that are very similar to the APIs already used for TCP/UDP applications.

For more information about the virtual hardware, see the vSphere Virtual Machine Administration Guide at http://uk.emc.com/collateral/TechnicalDocument/docu60786.pdf

Virtual Networking

VMware vSphere provides a rich set of networking capabilities that integrate well with sophisticated enterprise networks. These networking capabilities are provided by ESXi Server and managed by vCenter. Virtual networking provides the ability to network virtual machines in the same way physical machines are networked. Virtual networks can be built within a single ESX Server host or across multiple ESX Server hosts. VxRail ESXi hosts use a virtual switch for communication among virtual machines in the VxRail cluster using the same protocols that would be used over physical switches, without the need for additional networking hardware. The virtual switch also supports VLANs that are compatible with standard VLAN implementations from switch vendors. A virtual switch, like a physical Ethernet switch, forwards frames at the data-link layer.

Virtual Ethernet adapters are the key vSphere components for virtual networking. A virtual machine can be configured with one or more virtual Ethernet adapters, each of which has its own IP address and MAC address. As a result, virtual machines have the same properties as physical machines from a networking standpoint. In addition, virtual networks enable functionality not possible with physical networks today. Virtual Ethernet adapters are used by individual virtual machines and the virtual switches that connect VMs to each other and connect both virtual machines and the ESX Server service console to external networks.

The virtual switch links to the external network through outbound Ethernet adapters called vmnics, and the virtual switch can bind multiple vmnics together (much like NIC teaming on a traditional server), extending availability and bandwidth to the virtual machines it services. Virtual switches are similar to their physical-switch counterparts. Like a physical network device, each virtual switch is isolated

VXRAIL CONCEPTS AND ARCHITECTURE

for security and has its own forwarding table. An entry in one table cannot point to another port on another virtual switch. The switch looks up only destinations that match the ports on the virtual switch where the frame originated. This feature stops potential hackers from breaking virtual switch isolation. Virtual switches also support VLAN segmentation at the port level, so each port can be configured either as an access port to a single VLAN or as a trunk port to multiple VLANs.

Virtual Distributed Switch

VxRail clusters use the VMware Virtual Distributed Switch (VDS), which functions as a single switch that spans across multiple nodes in the same cluster. This switch enables virtual machines to maintain consistent network configuration as they migrate across multiple hosts. A distributed switch is configured in vCenter Server at the data-center level and makes the configuration consistent across all hosts. vCenter Server stores the state of distributed ports in the vCenter Server database. Networking statistics and policies migrate with virtual machines when the virtual machines are moved from host to host. As discussed in upcoming sections, vSAN relies on VDS for its storage-virtualization capabilities, and the VxRail Appliance uses VDS for appliance traffic.

Figure 32 provides a VDS overview.

Figure 32. Distributed Switch

vMotion and Virtual Machine Mobility

VMware v

Motion™ enables the live migration of running virtual machines from one physical server to another with zero downtime, continuous service availability, and complete transaction integrity. vMotion is a key enabling technology for creating the dynamic, automated, and self-optimizing data center. vMotion continuously and automatically allocates virtual machines within resource pools. It also improves availability by conducting maintenance without disrupting business operations.

The advanced capability for migrating workloads without disruption is one of the features that distinguish the VxRail solution from other

HCI options. In the vSphere virtual infrastructure, migration refers to moving a virtual machine from one host, datastore, or vCenter

Server system to another host, datastore, or vCenter Server system. Different types of migrations exist including:



Cold, which is migrating a powered-off VM to a new host or datastore



Suspended, which is migrating a suspended VM to a new host or datastore



Live, whi ch uses vSphere vMotion to migrate a “live,” powered-on VM to a new host and/or uses vSphere Storage vMotion to migrate the files of a live, powered-on VM to a new datastore vMotion allows for live migration of virtual machines between ESXi hosts without disruption or downtime. The process is summarized in

Figure 33. With vMotion, while the entire state of the virtual machine is migrated, the data remains in the same datastore. The state information includes the current memory content and all the information that defines and identifies the virtual machine. The memory content consists of transaction data and whatever bits of the operating system and applications in memory. The definition and

VXRAIL CONCEPTS AND ARCHITECTURE

identification information stored in the state includes all the data that maps to the virtual machine hardware elements, including BIOS, devices, CPU, and MAC addresses for the Ethernet cards.

Figure 33. vMotion Migration

A vMotion migration consists of the following steps:

1. The VM memory state is copied over the vMotion network from the source host to the target host. Users continue to access the VM and, potentially, update pages in memory. A list of modified pages in memory is kept in a memory bitmap on the source host.

2. After most of the VM memory is copied from the source host to the target host, the VM is quiesced. No additional activity occurs on the VM. During the quiesce period, vMotion transfers the VM-device state and memory bitmap to the destination host.

3. Immediately after the VM is quiesced on the source host, the VM is initialized and starts running on the target host. A Gratuitous Address Resolution

Protocol (GARP) request notifies the subnet that the MAC address for the VM is now on a new switch port.

4. Users access the VM on the target host instead of the source host. The memory pages used by the VM on the source host are marked as free.

Enhanced vMotion Compatibility

Enhanced vMotion Compatibility (EVC) is a cluster feature that prevents vMotion migrations from failing because of incompatible CPUs.

EVC ensures that all hosts in a cluster present the same CPU feature set to virtual machines, even if the actual CPUs on the hosts differ. It prevents migration failures due to CPU incompatibility. This is on by default in VxRail Appliances.

Storage vMotion

Storage vMotion uses an I/O-mirroring architecture to copy disk blocks between source and destination. The image below (Figure 34) helps to describe the process:

1. Initiate storage migration.

2. Use the VMkernel data mover and provide vSphere Storage APIs for Array Integration (VAAI) to copy data.

3. Start a new VM process.

4. Mirror I/O calls to file blocks that have already been copied to virtual disk on the target datastore. Switch to the target-VM process to begin accessing the virtual-disk copy.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 34. Storage vMotion

The storage-migration process copies the disk just once, and the mirror driver synchronizes the source and target blocks with no need for recursive passes. In other words, if the source block changes after it migrates, the mirror driver writes to both disks simultaneously which maintains transactional integrity. The mirroring architecture of Storage vMotion produces more predictable results, shorter migration times, and fewer I/O operations than more conventional storagemigration options. It’s fast enough to be unnoticeable to the end user. It also guarantees migration success even when using a slow destination disk. vSphere 6.0 supports the following Storage vMotion migrations:



Between clusters



Between datastores (including non-vSAN to vSAN and vice versa)



Between networks



Between vCenter Server instances for vCenter Servers configured in Enhanced Link Mode with hosts that are time-synchronized



Over long distances (up to 150ms round-trip time)

Note that for VxRail clusters, Storage vMotion can only be used for migration into or out of the vSAN datastore.

vSphere Distributed Resource Scheduler

VMware Distributed Resource Scheduler (DRS) is a key feature included with vSphere Enterprise Plus and vSphere with Operations

Management Enterprise Plus. DRS balances computing capacity across a collection of VxRail server resources that have been aggregated into logical pools. It continuously balances and optimizes compute resource allocation among the VMs. When a VM experiences an increased workload, DRS evaluates the VM priority against user-defined resource-allocation rules and policies. If justified, DRS allocates additional resources. It can also be configured to dedicate consistent resources to the VMs of particular business-unit applications to meet SLAs and business requirements. DRS allocates resources to the VM either by migrating the VM to another server with more available resources or by making more “resources” for the VM on the same server by migrating other VMs off the server. In the VxRail Appliance, all ESXi hosts are part of a vMotion network. The live migration of VMs to different node servers is completely transparent to end users through VMotion (see Figures 36 and 37 below). DRS adds tremendous value to the VxRail cluster by automating VM placement, ensuring consistent and predictable application-workload performance.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 35. DRS Movement of VMs Across Node Servers

Figure 36. VM Migration Across the vMotion Network. Requires the Use of External vCenter

DRS offers a considerable advantage to VxRail users during maintenance situations, because it automates the tasks normally involved in manually moving live machines during upgrades or repairs. DRS facilitates maintenance automation, providing transparent, continuous operations by dynamically migrating all VMs to other physical servers. That way, servers can be attended to for maintenance, or new node servers can be added to a resource pool, all while DRS automatically redistributes the VMs among the available servers as the physical resources change. In other words, DRS dynamically balances VMs as soon as additional resources become available when new server is added or when an existing server has finished its maintenance cycle. DRS allocates only CPU and memory resources for the VMs and uses vSAN for shared storage.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 37. Configuring DRS Settings

Some conditions and business operations warrant a more aggressive DRS migration strategy than others. Adjustable cluster parameters establish the thresholds that trigger DRS migrations. For example, a Level-2 threshold only applies specified migration recommendations to make a significant impact on the cluster’s load balance, whereas a Level-5 threshold applies all the recommendations to even slightly improve the cluster’s load balance.

DRS applies only to VxRail virtual machines. (vSAN uses a single datastore and handles placement and balancing internally. vSAN does not currently support Storage DRS or Storage I/O Control.)

vSphere High Availability (HA)

vSphere provides several solutions to ensure a high level of availability, both planned and unplanned downtime scenarios. vSphere depends on the following technologies to make sure that virtual machines running in the environment remain available:



Virtual machine migration



Multiple I/O adapter paths



Virtual machine load balancing



Failure tolerance



Disaster recovery

Together with vSAN, vSphere HA produces a resilient, highly available solution for VxRail virtual machine workloads. vSphere HA protects virtual machines by restarting them in the event of a host failure. It leverages the ESXi cluster configuration to ensure rapid recovery from outages, providing cost-effective high availability for applications running in virtual machines. When a host joins a cluster, its resources become part of the cluster resources. The cluster manages the resources of all hosts within it. In a vSphere environment,

ESXi clusters are responsible for vSphere HA, DRS, and the vSAN technology that provides VxRail software-defined storage capabilities.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 38. vSphere HA vSphere HA provides several points of protection for applications:



It circumvents any server failure by restarting the virtual machines on other hosts within the cluster.



It continuously monitors virtual machines and resets any detected VM failures.



It protects against datastore accessibility failures and provides automated recovery for affected virtual machines. With Virtual

Machine Component Protection (VMCP), the affected VMs are restarted on other hosts that still have access to the datastores.



It protects virtual machines against network isolation by restarting them if their host becomes isolated on the management or

VMware vSAN network. This protection is provided even if the network has become partitioned.

Once vSphere HA is configured, all workloads are protected. No actions are required to protect new virtual machines and no special software needs to exist within the application or virtual machine.

Included in the failover capabilities in vSphere HA is a service called the Fault Domain Manager (FDM) that runs on the member hosts.

After the FDM agents have started, the cluster hosts become part a fault domain, and a host can exist in only one fault domain at a time. Hosts cannot participate in a fault domain if they are in maintenance mode, standby mode, or disconnected from vCenter Server.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 39. Fault Domain Management

FDM uses a master-slave operational model (Figure 39). An automatically designated master host manages the fault domain, and the remaining hosts are slaves. FDM agents on slave hosts communicate with the FDM service on the master host using a secure TCP connection. In VxRail clusters, vSphere HA is enabled only after the vSAN cluster has been configured. Once vSphere HA has started, vCenter Server contacts the master host agent and sends it a list of cluster-member hosts along with the cluster configuration. That information is saved to local storage on the master host and then pushed out to the slave hosts in the cluster. If additional hosts are added to the cluster during normal operation, the master agent sends an update to all hosts in the cluster.

The master host provides an interface to vCenter Server for querying and reporting on the state of the fault domain and virtual machine availability. vCenter Server governs the vSphere HA agent, identifying the virtual machines to protect and maintaining a VM-to-host compatibility list. The agent learns of state changes through hostd, and vCenter Server learns of them through vpxa. The master host monitors the health of the slaves and takes responsibility for virtual machines that had been running on a failed slave host. Meanwhile, the slave host monitors the health of its local virtual machines and sends state changes to the master host. A slave host also monitors the health of the master host. vSphere HA is configured, managed, and monitored through vCenter Server. Cluster configuration data is maintained by the vCenter

Server vpxd process. If vxpd reports any cluster configuration changes to the master agent, the master advertises a new copy of the cluster configuration information and then each slave fetches the updated copy and writes the new information to local storage. Each datastore includes a list of protected virtual machines. The list is updated after vCenter Server notices any user-initiated power-on

(protected) or power-off (unprotected) operation.

vCenter Server Watchdog

One method of providing vCenter Server availability is to use the Watchdog feature in a vSphere HA cluster. Watchdog monitors and protects vCenter Server services. If any services fail, Watchdog attempts to restart them. If it cannot restart the service because of a host failure, vSphere HA restarts the virtual machine (VM) running the service on a new host. Watchdog can provide better availability by using vCenter Server processes (PID Watchdog) or the vCenter Server API (API Watchdog).

VXRAIL CONCEPTS AND ARCHITECTURE

vSAN

VxRail Appliances leverage

VMware’s vSAN software, which is fully integrated with vSphere and provides full-featured and costeffective software-defined storage. vSAN implements a notably efficient architecture, built directly into hypervisor. This distinguishes vSAN from solutions that typically install a virtual storage appliance (VSA) that runs as a guest VM on each host. Embedding vSAN into the ESXi kernel layer has obvious advantages in performance and memory requirements. It has very little impact on CPU utilization

(less than 10 percent) and self-balances based on workload and resource availability. It presents storage a familiar datastore construct and works seamlessly with other vSphere features such as vMotion. vSAN aggregates locally attached disks of hosts in a vSphere cluster to create a pool of distributed shared storage. (See Figure 40 below.) Capacity is easily scaled up by adding additional disks to the cluster and scaled out by adding additional ESXi hosts. This provides the flexibility to start with a very small environment and scale it over time. Storage characteristics are configured using Storage

Policy Based Management (SPBM), which allows object-level policies to be set and modified on the fly to control storage provisioning and day-to-day management of storage service-level agreements (SLAs). vSphere and vSAN provide the foundation for VxRail performance and scale, and enable enterprise-class capabilities for hosted virtual machines including mobility using vMotion, High

Availability, and Dynamic Resource Scheduler (DRS). vSAN is preconfigured when the VxRail system is first initialized and managed through vCenter. The VxRail appliance-initialization process discovers locally attached storage disks from each ESXi node in the cluster to create a distributed, shared-storage datastore.

The amount of storage in the vSAN datastore is an aggregate of all of the capacity drives in the cluster. Figure 40 below shows an example of a hybrid configuration where each node contributes storage capacity to the vSAN datastore. The SSD drive provides caching to optimize performance and hard disk drives (HDD) for capacity.

Figure 40. vSAN Datastore vSAN enables rapid storage provisioning within vCenter as part of the VM-creation and -deployment operations. vSAN is policy driven and designed to simplify storage provisioning and management. It automatically and dynamically matches requirements with underlying storage resources based on VM-level storage policies. VxRail provides two different vSAN node-storage configuration options: a hybrid configuration that leverages both flash SSDs and mechanical HDDs, and an all-flash SSD configuration. The hybrid configuration uses flash SSDs at the cache tier and mechanical HDDs for capacity and persistent data storage. The all-flash configuration uses flash SSDs for both the caching tier and capacity tier.

Disk Groups

Disk drives in VxRail hosts are organized into disk groups, and disk groups contribute storage to the vSAN cluster. In a VxRail appliance, a disk group contains a maximum of one flash-cache drive and six capacity devices. Depending on the model, each VxRail

VXRAIL CONCEPTS AND ARCHITECTURE

node can be configured with up to four disk groups. Figure 41 below shows the number of disk groups per node and the number of drives per disk group for each VxRail model.

VxRail

Model

Maximum

Number of Disk

Groups per Node

Max SSD- Cache

Drives per Disk

Group

Max Capacity

Drives per Disk

Group

G Series

E Series

P Series

V Series

S Series

(Hybrid only)

2 1 6

Figure 41. Disk Group Configurations

The disk-group layout, based on capacity, performance, and availability, is determined when the system is designed and sized. Below are the considerations for designing disk-group layout:



The number of SSD cache drives. Each disk group requires one and only one high-endurance SSD-flash cache drive. More disk groups require more SSD-flash cache drives. Currently, the VxRail Appliance is offered with 200GB, 400GB, 800GB, 1600GB cachetier flash devices. For VxRail, the SSD cache drive must be installed in designated slots. See product documentation for specific slot locations.



The total number of capacity drives available. Each disk group requires at least one capacity drive. Only capacity drive counts when determining the total capacity available for a vSAN Cluster.



Cache requirements. The cache tier improves read and write performance in a hybrid-storage configuration and write performance and endurance in an all-flash configuration. The optimal amount of cache depends on the active working set size. Workloads that have a larger working set size may require more cache, and this can be configured by either using larger SSD cache drives or configuring multiple disk groups with each disk group having one cache drive.

Note: All-flash configurations support a maximum of 600GB of write cache per disk group. Consider multiple disk groups for larger write cache per node.



Performance. For the same total capacity, a larger number of smaller drives will provide more IOPs than fewer larger drives.

Depending on the model, configuring more drives may require multiple disk groups



Fault Domains and recoverability. If the SSD cache drive fails, the full disk group goes offline and must be recovered. Larger disk groups take longer to recover. A node with only a single disk group will not be contributing any IOPs to the cluster during recovery, and this can reduce cluster performance.

Figure 42 below shows the physical disk group layout of a VxRail G Series node. This model is a four-node appliance and supports a single disk group per node. Each disk group has one SSD cache drive

(labeled as “C”) and up to five capacity drives (labeled as “D). All disk groups are designated as DG 1 as there is only one disk group per node.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 42. VxRail G Series Disk Group Physical Layout

Figure 43 below shows the physical disk group layout of a VxRail E Series. This model supports one or two disk groups per node and the disk groups are designated as DG1 and DG 2. Each disk group has one SSD cache drive and up to 4 capacity drives. Cache drive slots are designated with a “C” and capacity drives are designated with a “D”.

Figure 43. VxRail E Series Disk Group Physical Layout

Figure 44 below shows the physical disk group layout of a VxRail P and V Series. These models are single-node appliances and support up to four disk groups per node, designated as DG 1-4. Each disk group has one SSD cache drive and up to 3 capacity drives.

Cache drive slots are designated with a “C” and capacity drives are designated with a “D”.

Figure 44. VxRail P and V Series Disk Group Physical Layout

Figure 45 below shows the physical disk group layout of a VxRail S Series. This model is a single-node appliance and supports one or two disk groups per node, designated as DG 1 and DG 2. Each disk group has one SSD-flash cache drive and up to six capacity drives. This model uses 3.5” form factor capacity drives with 2.5” cache drives installed in the back. Capacity drives are designated with a “D” and the Cache drives are not shown in this diagram.

Figure 45. VxRail S Series Disk Group Physical Layout

The screenshot below (Figure 46) illustrates a disk group on a node that contains four disks. The first is a flash SSD, and its role is defined as Cache. The other three disks are HDDs defined as Capacity. The role of the disks, either cache or capacity, is automatically set in the VxRail Appliance.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 46. Disk-group configuration for four-disk node with one cache SSD and three capacity HDDs.

Hybrid and All-Flash Differences

The cache is used differently in hybrid and all-flash configurations. In hybrid disk-group configurations (which use mechanical HDDs for the capacity tier and flash SSD devices for the caching tier), the caching algorithm attempts to maximize both read and write performance. The flash SSD device serves two purposes: a read cache and a write buffer. 70 percent of the available cache is allocated for storing frequently read disk blocks, minimizing accesses to the slower mechanical disks. The remaining 30 percent of available cache is allocated to writes. Multiple writes are coalesced and written sequentially if possible, again maximizing mechanical

HDD performance.

In all-flash configurations, one designated flash SSD device is used for the cache tier, while additional flash SSD devices are used for the capacity tier. In all-flash disk-group configurations, there are two types of flash SSDs: a very fast and durable flash device that functions as write cache and more cost-effective SSD devices that function as capacity. Here, the cache-tier SSD is 100 percent allocated for writes. None of the flash cache is used for reads; read performance from capacity-tier flash SSDs is more than sufficient for high performance. Many more writes can be held by the cache SSD in an all-flash configuration, and writes are only written to capacity when needed, which extends the life of the capacity-tier SSD.

While both configurations dramatically improve the performance of VMs running on vSAN, all-flash configurations provide the most predictable and uniform performance regardless of workload.

Read Cache: Basic Function

The read cache, which only exists in hybrid configurations, keeps a collection of recently read disk blocks. This reduces the I/O read latency in the event of a cache hit, i.e. the disk block can be fetched from cache rather than mechanical disk. For a given VM data block, vSAN always reads from the same replica/mirror. However, when there are multiple replicas (to tolerate failures), vSAN divides up the caching of the data blocks evenly between the replica copies.

If the data block being read from the first replica is not in cache, the directory service is referenced to discover whether or not the data block exists in the cache of another mirror (on another host) in the cluster. If the data block is found there, the data is retrieved. If the data block isn’t in cache on the other host, then there is a read-cache miss. In that case, the data is retrieved directly from the mechanical HDD.

VXRAIL CONCEPTS AND ARCHITECTURE

Write Cache: Basic Function

The write cache, found in both hybrid and all-flash configurations, behaves as a non-volatile write buffer. This greatly improves performance in both hybrid and all-flash configurations and also extends the life of flash capacity devices in all-flash configurations.

When writes are written to cache, vSAN ensures that a copy of the data is written elsewhere in the cluster. All VMs deployed with vSAN are set with a default availability policy that ensures at least one additional copy of the VM data is available. This includes making sure that writes end up in multiple write caches in the cluster.

Once an application running inside the guest OS initiates a write, it is duplicated to the write cache on the hosts that include replicas of the storage objects. This means that in the event of a host failure, a copy of the data is in cache and no data loss occurs. The VM simply uses the replicated copy of the cache data.

Flash Endurance

Flash endurance is related to the number of write/erase cycles that the cache-tier flash SSD can tolerate before it potentially has issues with reliability.vSAN6.0 and VxRail configurations, the endurance specification uses Terabytes Written (TBW). For all-flash vSAN deployments running high workloads, the flash-cache device specification is 4TBW per day

—the equivalent of 7300 TB writes over five years.

vSAN Impact on Flash Endurance

There are two commonly used approaches to improve NAND Flash endurance: improve wear leveling and minimize write activity. A distributed storage implementation that focuses on localizing data on the same node where the VMs reside prevents the distribution of the writes across all the drives in the cluster. This localization inevitably increases drive usage, leading to early drive replacement.

In contrast, vSAN distributes the objects and components of a VM across all the disk groups in the VxRail cluster. This distribution significantly improves wear leveling and reduces write activity by deferring writes. vSAN also reduces writes by employing datareduction techniques such as de-duplication and compression.

Client Cache

The client cache is used on both hybrid and all-flash configurations. It leverages local DRAM server memory (client cache) within the node to accelerate read performance. The amount of memory allocated is .4% -1GB per host. vSAN first tries to fulfill the read request from the local client cache, so the VM can avoid crossing the network to complete the read. If the data is unavailable in the client cache, the cache-tier SSD is queried to fulfill the read request. The client cache benefits read cache-friendly workloads.

Objects and Components

VxRail virtual machines are made up of a set of objects. For example, a VMDK is an object, a snapshot is an object, VM swap space is an object, and the VM home namespace (where the .vmx file, log files, etc. are stored) is also an object. (See Figure 47 below.)

Virtual-machine objects are split into multiple components based on performance and availability requirements defined in the Storage

Policy applied to the objects of the VM. For example, if the VM is deployed with a policy to tolerate a single failure, the objects have two replica components. Distributed storage uses a disk-striping process to distribute data blocks across multiple devices. The stripe itself refers to a slice of data; the striped device is the individual drive that holds the stripe. If the policy contains a stripe width, the object is striped across multiple devices in the capacity layer, and each stripe is an object component.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 47. vSAN Objects and Components

Each vSAN host has a maximum of 9,000 components. The largest component size is 255GB. For objects greater than 255GB, vSAN automatically divides them into multiple components. For example, a VMDK of 62TB generates more than 500 x 255GB components.

Figure 47 above illustrates how components that make up VM objects are spread across drive on nodes based on Failure to tolerate policy.

Witness

In vSAN, witnesses are an integral component of every storage object when the object is configured to tolerate at least one failure and when using mirroring as the Failure Tolerance Method. Witnesses are components that contain no data, only metadata. Their purpose is to serve as tiebreakers when availability decisions are made to meet the failures to tolerate (FTT) policy setting, and they’re used when determining if a quorum of components exist in the cluster.

In vSAN 6.0, storage components can be distributed in such a way that they can guarantee availability without relying on a witness. In this case, each component has a number of votes

—at least one or more. Quorum is calculated based on the rule that requires "more than 50 percent of votes." (Still, many objects have a witness in 6.0.)

Replicas

Replicas make up the virtual machine’s storage objects. Replicas are instantiated when an availability policy (Failures to tolerate) is specified for the virtual machine. The availability policy dictates how many replicas are created and lets virtual machines continue running with a full complement of data even when host, network, or disk failures occur in the cluster.

Storage Policy Based Management (SPBM)

vSAN policies define virtual-machine storage requirements for performance and availability. These policies determine how storage objects are provisioned and allocated within the datastore to guarantee the required level of service. vSAN implements Storage Policy Based Management, and each virtual machine deployed in a vSAN datastore has at least one assigned policy. When the VM is created and assigned a storage policy, the policy requirements are pushed to the vSAN layer. (See

Figure 48 below.)

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 48. SPBM

Policy assignments can be manually or automatically generated, based on rules. For instance, all virtual machines that include with

PROD-SQL in their name or resource group might be set at RAID-1 and a 5-percent read-cache reservation, and TEST-WEB would be automatically set to RAID-0.

Dynamic Policy Changes

Administrators can dynamically change a VM storage policy. When changing attributes such as the number of Failures to tolerate, vSAN attempts to find a new placement for a replica with the new configuration. In some cases, existing parts of the current configuration can be reused, and the configuration just needs to be updated or extended. For example, if an object currently uses

Failures to tolerate=1, and the user asks for Failures to tolerate=2, vSAN can simply add another mirror (and witness).

In other cases, such as changing the stripe width from one to two, vSAN cannot reuse existing replicas, and it creates a brand new replica (or replicas) without impacting the existing objects. A storage object has a status of Compliant if the attributes match the policy.

When changing a policy online, the object may show as “not compliant” while vSAN reconfigures the object.

Storage Policy Attributes

The screenshot in Figure 49 displays an example of the rule set for storage policy.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 49. vSAN Policy Attributes

Number of disk stripes per object

This rule establishes the minimum number of capacity devices used for striping each virtual-machine replica. A value higher than 1 might result in better performance, but it also results in higher resource consumption. The default value is the minimum 1, and the maximum value is 12. The stripe size is 1MB. vSAN may decide that an object needs to be striped across multiple disks without any stripe-width policy requirement. The reason for this can vary, but typically it occurs when a VMDK is too large to fit on a single physical drive. However, when a particular stripe width is required, then it should not exceed the number of disks available to the cluster.

Flash read cache reservation

Flash cache reservation refers to flash capacity reserved as read cache for the virtual machine object, and it applies to hybrid configurations only. By default, vSAN dynamically allocates read cache to storage objects based on demand. As a result, no need typically exists to change the default 0 value for this parameter.

However, in very specific cases, when a small increase in the read cache for a single VM can provide a significant change in performance, it is an option. It should be used with caution to avoid wasting resources or taking resources from other VMs.

The default value is 0 percent. Maximum value is 100 percent.

Failures to tolerate

This FTT option generally defines the number of host and device failures that a virtual machine object can tolerate. For

failures tolerated,

n+1

copies of the VM object area created and 2n+1 hosts with storage are required.

The default value is 1. Maximum value is 3.

When erasure coding is enabled for a cluster (by setting FTM=Capacity), RAID-5 is applied if the number of Failures to tolerate is set to

1, and RAID-6 is applied if the number of Failures to tolerate is set to 2. Note a vSAN cluster requires a minimum of four nodes for

RAID-5 and six nodes for RAID-6.

Failure tolerance method

Failure tolerance method (FTM) specifies whether the data-replication method optimizes for performance or capacity. The RAID-1 failure tolerance method provides better performance and consumes less memory and network resources but uses more disk space.

RAID-5/6 erasure coding provides more usable capacity but consumes more CPU and network resources. (An upcoming section on erasure coding section provides additional information.)

VXRAIL CONCEPTS AND ARCHITECTURE

IOPS limit for object (QoS)

This attribute establishes Quality of Service (QoS) for an object by defining an upper limit on the number IOPS a VM/VMDK can perform. The default behavior is all object are not limited and low priority applications could potentially consume resources in a manner that could impact more important workloads. This rule allows different limits for different applications and can be used to keep workloads from impacting each other (the noisy-neighbor issue) or to supply service-level agreements (SLAs) for different workloads and maintain performance for tier-1 applications.

IOPS is calculated based on all of the operations on this VM/VMDK (read & write) including snapshots.

A few notes regarding IOPS:



When calculating IOPS, read and write are considered equivalent, but keep in mind that cache-hit ratio and sequentiality are not considered.



When an object exceeds its disk IOPS limit, I/O operations are throttled.



If the IOPS limit for object is set to 0, IOPS limits are not enforced.



vSAN allows the object to double the IOPS-limit rate during the first second of operation or after a period of inactivity.

Figure 50 below illustrates how IOs are throttled when the IOPS limit policy is set.

Figure 50. IOPS limits establishes Quality of Service

Disable object checksum vSAN uses end-to-end checksum to ensure data integrity by confirming that each copy of a n object’s 4K chunk of data is exactly the same. The checksum is five bytes in length and persists with the data. When data is written, the checksum is verified to ensure no corruption occurred when the data transverses the network. When data is read, checksum verifies that the data read matches what was written. If an error is detected; vSAN uses a replica to recover the data and logs an error. Checksum calculation and error-correction are transparent to the user.

The default setting for all objects in the cluster is On, which means that checksum is enabled. The best practice is not to change this setting because detecting data corruption is a critical and valuable feature of vSAN and should not be disabled.

Force provisioning

If this option is set to Yes, the object is provisioned even if the FTT, Number of disk stripes per object, and Flash read cache reservation policies specified in the storage policy cannot be satisfied by the datastore.

VXRAIL CONCEPTS AND ARCHITECTURE

This parameter is used in bootstrapping scenarios and during an outage when standard provisioning is no longer possible.

The default is No and will not allow an object to be created if the other policies cannot be satisfied. This is appropriate for most production environments. If set to Yes, an object can be created even not enough resources are available to satisfy the other policy rules. In this case, the object will be displayed as Not Compliant.

Object space reservation

Object space reservation is specified as a percentage of the total object size. It reflects the reserved, thick-provisioned space required for deploying virtual machines.

The default value is 0%. Maximum value is 100%.

The value should be set either to 0% or 100% when using RAID-5/6 in combination with deduplication and compression.

Sparse Swap

Sparse swap is a v

SAN feature worth highlighting for its space efficiency, and it’s available for both all-flash and hybrid environments.

By default, vSAN swap files are thick provisioned

—created with 100 percent space reservation. (For example, if the VM has 4GB of

RAM, then the swap file also has 4GB of RAM.) While this guarantees sufficient capacity for the VM, it can consume too much memory

—especially in large clusters with a lot of virtual machines. When Sparse Swap is enabled as an advanced host setting, the VM reserves less memory space for the swap objects than the full 100 percent.

Sparse Swap is established by enabling the Swap thick provision disabled setting. Sparse swap files have a Failure to tolerate (FTT) setting of 1 and a Failure tolerance method (FTM) setting of RAID1 (Mirroring).

Leveraging Sparse Swap is an effective way to reduce memory overhead in environments that are not already over-committing memory, especially for all-flash VxRail environments where swap files represent a sizeable portion of the total required datastore capacity.

I/O Paths and Caching Algorithms

This section elaborates on some of the vSAN concepts that have been introduced so far with additional, general information about vSAN caching algorithms. The next paragraphs briefly describe how vSAN leverages flash, memory, and rotating disks. They also illustrate the I/O Paths between the guest OS and the persistent storage areas.

Read Caching

Each disk group contains an SSD drive used as a cache tier. On a hybrid system, 70 percent of the capacity is used by default for Read

Cache (RC). The most active data is maintained in the cache tier and improves performance by minimizing the latency impact of reading from mechanical disk.

The RC is organized in terms of cache lines. They represent the unit of data management in RC, and the current size is 1MB. Data is fetched into the RC and evicted at cache-line granularity. In addition to the SSD read cache, vSAN also maintains a small in-memory

(RAM) read cache that holds the most-recently accessed cache lines from the RC. The in-memory cache is dynamically sized based on the available memory in the system. vSAN maintains in-memory metadata that tracks the state of the RC (both SSD and in memory), including the logical addresses of cache lines, valid and invalid regions in each cache line, aging information, etc. These data structures are designed to compress for efficiencies, using memory space without imposing a substantial CPU overhead on regular operations. No need exists to swap RC metadata in or out of persistent storage. (This is one area where VMware holds important IP.)

Read-cache contents are not tracked across power-cycle operations of the host. If power is lost and recovered, then the RC is repopulated (warmed) from scratch. So, essentially RC is used as a fast-storage tier, and its persistence is not required across power cycles. The rationale behind this approach is to avoid any overheads on the common data path that would be required if the RC metadata was persisted every time RC was modified

—such as cache-line fetching and eviction, or when write operations invalidate a sub-region of a cache line.

VXRAIL CONCEPTS AND ARCHITECTURE

Anatomy of a Hybrid Read

Read operations follow a defined procedure. To illustrate, the VMDK in the example below has two replicas on esxi1 and esxi3.

1. Guest OS issues a read on virtual disk

2. Owner chooses replica to read from o

Load balance across replicas o

Not necessarily local replica (if one) o

A block always reads from same replica

3. At chosen replica (esxi-03): read data from flash write buffer, if present

4. At chosen replica (esxi-03): read data from flash read cache, if present

5. Otherwise, read from HDD and place data in flash read cache o

Alloca te a 1MB buffer for the missing cache line and replace “coldest” data (eviction of coldest data to make room for new read)

Each missing line is read from the HDD as multiples of 64KB chunks, starting with the chunks that contain the referenced data

6. Return data to owner

7. Complete read and return data to VM

8. Once the 1MB cache line is added to the in-line read cache, its population continues asynchronously. This occurs to explore both the spatial and temporal locality of reference, increasing the changes that the next reads will find in the read cache.

Figure 51. Hybrid Read

Anatomy of an All-Flash Read

1. Guest OS issues a read on virtual disk

2. Owner chooses replica to read from o

Load balance across replicas

Much of the content in this specific section has been extracted from an existing technical whitepaper: An overview of VMware VSAN Caching

Algorithms.

VXRAIL CONCEPTS AND ARCHITECTURE

Not necessarily local replica (if one)

3. At chosen replica (esxi-03): read data from flash write buffer, if present

4. Otherwise, read from capacity flash device

5. Return data to owner

6. Complete read and return data to VM

Figure 52. All-Flash Read

The major difference is that read-cache misses cause no serious performance degradation. Reads from flash capacity devices should be almost as quick as reads from the cache SSD. Another significant difference is that no need exists to move the block from the capacity layer to the cache layer, as in hybrid configurations.

Write Caching

Why write-back caching? In hybrid-configurations, this is done entirely for performance. The aggregate-storage workloads in virtualized infrastructures are almost always random, thanks to the statistical multiplexing of the many VMs and applications that share the infrastructure.

HDDs can perform only a small number of random I/O with a high latency compared to SSDs. So, sending the random write part of the workload directly to spinning disks can cause performance degradation. On the other hand, magnetic disks exhibit decent performance for sequential workloads. Modern HDDs may exhibit sequential-like behavior and performance even when the workload is not perfectly sequential. “Proximal I/O” suffices.

In hybrid disk groups, vSAN uses the write-buffer (WB) section of the SSD (by default, 30 percent of device capacity) as a write-back buffer that stages all the write operations. The key objective is to de-stage written data (not individual write operations) in a way creates a benign, near-sequential (proximal) write workload for the HDDs that form the capacity tier.

In all-flash disk groups, vSAN utilizes the tier-1 SSD entirely as a write-back buffer (100 percent of the device capacity

—up to a maximum of 600GB). The purpose of the WB is quite different in this case. It absorbs the highest rate of write operations in a highendurance device and allows only a trickle of data to be written to the capacity flash tier. This approach allows low-endurance, largercapacity SSDs at the capacity tier.

Nevertheless, capacity-tier SSDs are capable of serving very large numbers of read IOPS. Thus, no read caching occurs in the tier-1

SSD, except when the most-recent data referenced by a read operation still resides in the WB.

VXRAIL CONCEPTS AND ARCHITECTURE

In either case (hybrid or all flash), every write operation is handled through transactional processes: A record for the operation is persisted in the transaction log in the SSD.



The data (payload) of the operation is persisted in the WB.



Updated in-memory tables reflect the new data and its logical address space (for tracking) as well as its physical location in the capacity tier.

The write operation completes upstream after the transaction has committed successfully.

Commonly (under typical steady-state workloads), the log records of multiple write operations are coalesced before they are persisted in the log. This reduces the amount of metadata-write operations for the SSD. By definition, the log is a circular buffer, written and freed in a sequential fashion. Thus write amplification can be avoided (good for device endurance). The WB region allocates blocks in a round-robin fashion, keeping wear leveling in mind. Even when a write operation overwrites existing WB data, vSAN never rewrites an existing SDD page in place. Instead, it allocates a new block and updates metadata to reflect that the old blocks are invalid. vSAN fills an entire SSD page before it moves to the next one. Eventually, entire pages are freed when all their data is invalid. (It is very rare to re-buffer data to allow SSD pages to be freed). Also, because the device firmware does not have visibility into invalidated data, it sees no “holes” in pages. In effect, internal write leveling (by moving data around to fill holes in pages) is all but eliminated. This extends the overall endurance of a device. In general, the vSAN design has gone to great lengths to impose a benign workload in terms of endurance. As a result, the life expectancy of SSDs implemented in vSAN may exceed the manufacturers’ specifications, which are developed with more generic workloads in mind.

Anatomy of a Write I/O

—Hybrid and All-Flash (FTM=Mirroring)

1. VM running on host esxi-01

2. esxi-01 is owner of virtual disk object o

Failures to tolerate = 1

3. Object has two (2) replicas on esxi-01 and esxi-03

4. Guest OS issues write op to virtual disk

5. Owner clones write operation o

In parallel: sends write op to esxi-01 (locally) and esxi-03

6. esxi-01, esxi-03 persist operation to flash (log)

7. esxi-01, esxi-03 ACK-write operation to owner

8. Owner waits for ACK from both writes and completes I/O!

Later, backend hosts commit batch of writes

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 53. Hybrid and Flash Write I/O

Distributed Caching Considerations

vSAN caching algorithms and data-locality techniques reflect a number of objectives and observations pertaining to distributed caching:



vSAN exploits temporal and spatial locality for caching.



vSAN implements a distributed, persistent cache on flash across the cluster. Caching is done in front of the disks where the data replicas live, not on the client side. A distributed-caching mechanism results in better overall flash-cache utilization.



Another benefit of distributed caching is during VM migrations, which can happen in some data centers over ten times a day. W ith

DRS and vMotion, VMs can move around from host-to-host in a cluster. Without a distributed cache, the migrations would have to move around a lot of data and rewarm caches every time a VM migrates. As the graph below (Figure 54) illustrates, vSAN prevents any performance degradation after a VM migration.

Figure 54. vSAN prevents performance degradation after VM migration.



The network introduces a small latency when accessing data on another host. Typical latencies in 10GbE networks range from 5

–

50 microseconds. Typical latencies of a flash drive, accessed through a SCSI layer, are near 1ms for small (4K) I/O blocks. So, for the majority of the I/O executed in the system, the network impact adds near 0.1 percent to the latency.

VXRAIL CONCEPTS AND ARCHITECTURE



Few workloads are actually cache friendly, meaning that they don’t take advantage of the way small increases in cache size can significantly increase the rate of I/O. These workloads can benefit from local cache, and enabling the Client Cache would be the right approach.



vSAN works with a View Accelerator (deduplicated, in-memory read cache), which is notably effective for VDI use cases. Remember also that vSAN 6.2 features Client Cache that leverages DRAM memory local to the virtual machine to accelerate read performance.

The amount of memory allocated is anywhere from .4 percent to 1GB per host.

vSAN High Availability and Fault Domains

vSAN policy attributes establish parameters to protect against node failures, but they may not be the most effective or efficient way to build tolerance for events like rack failures. This section reviews the availability features for vSAN clusters on the VxRail Appliance. It starts out by looking at the availability implications on small VxRail deployments with fewer than four nodes.

Fault Domain Overview

vSAN and VxRail Appliances use fault domains as a way of configuring tolerance for rack and site failures. By default, a node is considered a fault domain. vSAN will spread components across fault domains, therefore, by default vSAN will spread components across nodes. Consider, for example, a cluster with four (4) four-node VxRail appliances, each one placed in a different rack. By explicitly defining each four-node appliance as separate fault domains, vSAN will spread redundancy components across the different racks.

In terms of implementation, any host that is not part of another fault domain is considered its own single-host fault domain. VxRail requires at least three fault domains, and each has at least one host. Fault domain definitions recognize the physical hardware constructs that represent the domain itself. Once the domain is enabled, vSAN applies the active virtual-machine storage policy to the entire domain, instead of just to the individual hosts. The number of fault domains in a cluster is calculated based on the FTT attribute:

(Number of fault domains) = 2 * (Failures to tolerate) + 1.

Figure 55. Managing Fault Domains

Fault Domains and Rack-Level Failures

The fault domain mechanism is smart enough to perceive when the configuration is vulnerable. Consider a cluster that contains four server racks, each with two nodes. If the FTT is set to 1, and fault domains are not enabled, vSAN might store both replicas of an object with hosts in the same rack, and if that’s the case, applications are exposed to a potential rack-level failure. With fault domains enabled however, vSAN ensures that each protection component (replicas and witnesses) is placed in a separate fault domain. It makes sure that the nodes can’t fail together. The chart below (Figure 56) illustrates a four-rack setup, each with two ESXi nodes (a subset of the available hosts in a VxRail Appliance).

There are four defined Fault Domains:



FD1 = esxi-01, esxi-02



FD2 = esxi-03, esxi-04

VXRAIL CONCEPTS AND ARCHITECTURE



FD3 = esxi-05, esxi-06



FD4 = esxi-07, esxi-08

Figure 56. Fault Domains for a Four-Rack VxRail Configuration

This configuration guarantees that the replicas of an object are stored in hosts of different rack enclosures, ensuring availability and data protection in case of a rack-level failure.

vSAN Stretched Cluster

The concept of a stretched cluster is a good example of vSAN native integration with vSphere. With VxRail, stretch clustering extends availability of large enterprise data center. The stretched cluster is a specific configuration implemented in environments where the requirement for data-center level disaster/downtime avoidance is absolute. Simil ar to how fault domains enable “rack awareness” for rack failures; stretch clusters provide “data-center awareness,” providing virtual-machine availability despite specific data-center failure scenarios.

In a VxRail environment, stretched clusters with witness host refers to a deployment where a vSAN cluster consists of two active/active sites with an identical number of ESXi hosts distributed evenly between them. The sites are connected via a high bandwidth/low latency networking.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 57. Stretched VxRail Cluster

In the graphic above (Figure 57), each site is configured as a vSAN fault domain. The nomenclature used to describe the stretchedcluster configuration is X+Y+Z, where X is the number of ESXi hosts at Site A, Y is the number of ESXi hosts at Site B, and Z is the number of witness hosts at site C.

A virtual machine deployed on a stretched cluster has one copy of its data on Site A, and another on Site B, as well as witness components placed on the host at Site C.

It’s a singular configuration, achieved through a combination of fault domains, hosts and VM groups, and affinity rules. In the event of a complete site failure, the other site still has a full copy of virtual-machine data and at least half of the resource components available.

That means all the VMs remain active and available on the vSAN datastore. RPO is zero and the data RTO is zero. The application

RTO is dependent upon the application recoverability.

The minimum configuration supported by VxRail 4.0 is 3+3+1 (7 nodes); the maximum is 15+15+1 (31 nodes). Stretched clusters are supported by both hybrid and all-flash VxRail configurations. VxRail 3.5 minimum supported configuration is 4+4+1.

NOTE: This section contains only a brief design and considerations discussion. For more information, refer to VMware vSAN 6.2

Stretched Cluster Guide: http://www.vmware.com/files/pdf/products/vsan/VMware-Virtual-SAN-6.2-Stretched-Cluster-Guide.pdf

Site Locality

In a conventional storage-cluster configuration, reads are distributed across replicas. In a stretched-cluster configuration, the vSAN

Distributed Object Manager (DOM) also takes into account the object’s fault domain, and only reads from replicas in the same domain.

That way, it avoids any lag time associated with using the inter-site network to perform reads.

Networking

Both Layer-2 (same subnet) and Layer-3 (routed) configurations are used for stretched-cluster deployments. A Layer-2 connection should exist between data sites, and Layer-3 connection between the witness and the data sites.

VXRAIL CONCEPTS AND ARCHITECTURE

The bandwidth between data sites depends on workloads, but Dell EMC requires a minimum of 10Gbps for VxRail Appliances, and that should accommodate the stretched cluster. The supported latency for witness hosts is up to 200ms RTT and a bandwidth of 2Mbps for every 1,000 vSAN objects. Also bear in mind that the latency between data sites should be no be greater than 5ms, generally estimated at 500km or about 310 miles.

Stretched-Cluster Heartbeats and Site Bias

Stretched cluster configurations effectively have three fault domains. The first functions as the preferred data site, the second is the secondary data site, and the third is simply the witness host site.

The vSAN master node is placed on the preferred site and the vSAN backup node is placed on the secondary site. As long as nodes

(ESXi hosts) are available in the preferred site, then a master is always selected from one of the nodes on this site

—similarly for the secondary site, as long as nodes are available on the secondary site.

The master node and the backup node send heartbeats every second. If heartbeat communication is lost for five consecutive heartbeats (five seconds), the witness is deemed to have failed. If the witness has suffered a permanent failure, a new witness host can be configured and added to the cluster. Preferred sites gain ownership in case of a partition.

After a complete failure, both the master and the backup end up at the sole remaining live site. Once the failed site returns, it continues with its designated role as preferred or secondary, and the master and secondary migrate to their respective locations.

In terms of the communication with the witness, if the heartbeat pauses for five consecutive beats, the master assumes that the witness failed. If it’s a permanent failure, a new witness host needs to be configured and added to the cluster, and preferred sites gain ownership in case of a partition.

vSphere HA settings for Stretched Cluster

A stretched cluster requires the following vSphere HA settings:



Host monitoring is enabled by default in all VxRail deployments, including of course stretched-cluster configurations. This feature also uses network heartbeat to determine the status of hosts participating in the cluster. It indicates a possible need for remediation, such as restarting virtual machines on other cluster nodes.



Configuring admission control ensures that vSphere HA has sufficient available resources to restart virtual machines after a failure.

This may be even more significant in a stretched cluster than it is in a single-site cluster, because it makes the entire, multi-site infrastructure resilient. Workload availability is perhaps the primary motivation behind most stretched-cluster implementations.



The deployment needs sufficient capacity to accommodate full-site failure. Since the stretched cluster equally divides the number of

ESXi hosts between sites, Dell EMC recommends configuring the admission-control policy to 50 percent for both CPU and memory to ensure that all workloads can be restarted by vSphere HA.

Snapshots

Snapshots have been around for a while as a means of capturing the state of a data object at a particular point in time (PIT), so that it can be rolled back to that state if needed after a logical or physical failure. In the case of the VxRail solution, administrators can create, roll back, or delete VM snapshots using the Snapshot Manager in the vSphere Web client. Each VM supports a chain of up to 32 snapshots.

A virtual machine snapshot generally includes the settings (.nvram and .vmx) and power state, state of all the VM’s associated disks, and optionally, the memory state. Specifically, each snapshot includes:



Delta disk: The state of the virtual disk at the time the snapshot is taken is preserved. When this occurs, the guest OS is unable write to its .vmdk file. Instead, changes are captured in an alternate file named VM_name-delta.Vmdk.



Memory-state file: VM_name-Snapshot#.Vlms, where # is the next number in the sequence, starting with 1. This file holds the memory state since the snapshot was taken.

If memory is captured, the size of this file is the size of the virtual machine’s maximum memory. If memory is not captured, the file is much smaller.



Disk-descriptor file: VM_name-00000#.vmdk, a small text file that contains information about the snapshot.

VXRAIL CONCEPTS AND ARCHITECTURE



Snapshot-delta file: VM_name-00000#-delta.V

mdk, which contains the changes to the virtual disk’s data at the time the snapshot was taken.



VM_name.Vmsd: This snapshot list file is created when virtual machine itself is deployed. It maintains VM snapshot information that goes into a snapshot list in the vSphere Web Client. This information includes the name of the snapshot.Vims file and the name of the virtual-disk file.

The snapshot state uses a .Vlms extension and stores the requisite VM information at the time of the snapshot. Each new VM snapshot generates a new .vmsn file. The size of this file varies, based on the options selected during creation. For example, including the memory state of the virtual machine increases the size of the .vmsn file. It typically contains the name of the VMDK, the display name and description, and an identifier for each snapshot.

Other files might also exist. For example, a snapshot of a powered-on virtual machine has an associated snapshot_name_number.vmem file that contains the main memory of the guest OS, saved as part of the snapshot.

A quiesce option is available to maintain consistent point-in-time copies for powered-on VMs. VMware tools may use their own sync driver or use Microsoft’s Volume Shadow Copy Service (VSS) to quiesce not only the guest OS files system, but also any Microsoft applications that understand VSS directives.

How Snapshots Work

vSAN snapshots use an efficient, on-disk vSANSparse format. When a base-disk snapshot is taken, it creates a child delta disk. The parent functions as a static, PIT copy. Meanwhile the child delta starts a snapshot chain, recording the virtual-machine write history.

The delta disk snapshot object is made up of a set of grains, where each grain is a block of sectors containing virtual-disk data. The deltas keep only changed grains, which makes them space efficient.

In the diagram below (Figure 58), the base disk object is called Disk.vmdk and sits at the bottom of the chain. The chain includes three snapshot objects (Disk-001.vmdk, Disk-002.vmdk and Disk-003.vmdk) that have been taken at various intervals. Various guest-OS writes have also occurred at various intervals, leading to changes in snapshot deltas.



Base object writes to grains 1, 2, 3, and 5,



Delta object Disk-001 writes to grains 1 and 4



Delta object Disk-002 writes to grains 2 and 4



Delta object Disk-003 writes to grains 1 and 6

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 58. Snapshot Chain

A virtual-machine read would return the following:



Grain 1

– retrieved from Delta object Disk-003



Grain 2

– retrieved from Delta object Disk-002



Grain 3

– retrieved from Base object



Grain 4

– retrieved from Delta object Disk-002



Grain 5

– retrieved from Base object – 0 returned as it was never written



Grain 6

– retrieved from Delta object Disk-003

The diagram below (Figure 59) reuses the example above to illustrate the vSANSparse driver and its in-memory cache.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 59. vSANSparse Driver

When a guest OS sends a write request, the vSANSparse driver writes the data to the top-most object in the snapshot chain and updates its in-memory read cache. On subsequent reads, the vSANSparse references the in-memory read cache to determine which delta (or deltas) to read. The read requests are sent in parallel to all deltas that have the necessary data.

Managing Snapshots

Administrators use the Snapshot Manager to review active virtual-machine snapshots and perform limited management operations, including:



Delete, which commits snapshot data to its parent snapshot



Delete All, which removes all the snapshots, including the parent



Revert to, which rolls back to a referenced snapshot so that it becomes the current snapshot

Note that deleting a snapshot consolidates the changes between snapshots and previous disk states. It also writes to the parent disk all data from the delta disk and the deleted snapshot. When the parent is deleted, all changes merge with the base VMDK.

Administrators also should remember to monitor read cache, because snapshots

—used extensively—can consume RC at a higherthan-optimal rate.

Storage Efficiency Using Deduplication and Compression

Storage capacity requirements continue to grow exponentially, and IT organizations are looking for ways increase storage efficiency in order to meet their growing capacity requirements at the lowest cost. One way to do this is to use data deduplication and compression, which can result in more capacity of at a lower cost. Many environments can achieve an effective capacity that is twice of the raw capacity. These data reduction capabilities can be utilized on all-flash VxRail clusters.

Compression and deduplication techniques have been in place for a number of years but have not been widely adopted because of the overhead and system resources required to implement. Today, VxRail all-flash models with up to 28 cores and 512 GB of memory per node are a powerhouse! Along the architectural efficiencies of vSAN, the space savings more than offsets the slight overhead (<5%). A

VxRail all-flash configuration often provides more effective capacity at a lower cost than a hybrid HDD solution.

With vSAN, deduplication and compression occurs inline when data is de-staged from the cache tier to the capacity tier. First data is deduplicated by removing redundant copies of blocks that contain the exact same data. This is done at the 4K block level. Figure 60 below shows a typical virtual machine environment. While all VMs are unique, they share some amount of common data. Rather than saving multiple copies of the same data, identical blocks are saved once on SSD, and references to the unique blocks are tracked using metadata that is maintained in the capacity tier.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 60. Inline Data Deduplication

The deduplication algorithm is applied at the disk-group level and results in only a single copy of each unique 4K block per disk group.

While duplicated data block may exist across multiple disk groups, by limiting the deduplication domain to a disk group, a global lookup table is not required, which minimizes network overhead and CPU utilization.

LZ4 compression is applied after the blocks are deduplicated and before being written to SSD. If the compression results in a block size of 2KB or less, the compressed version of the block is persistently saved on SSD. If the compression does not result in a block size of less than 2KB, the full 4K block is written to SSD.

Almost all workloads benefit some from deduplication. However typical virtual-server workloads with highly redundant data such as fullclone virtual desktops or homogenous-server operating systems benefit most. Compression provides further data reduction. Text, bitmap, and program files are very compressible, and 2:1 is often possible. Other data types that are already compressed, such as certain graphics formats and video files or encrypted files, may yield little or no reduction.

Deduplication and compression are disabled by default and are enabled together at the cluster level. While it can be enabled at any time, enabling it when the system is initially setup is recommended to avoid the overhead and potential performance impact of having to deduplicate and compress existing data through post processing rather than to do it inline. Figure 61 below shows the vSAN setting for enabling compression.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 61. Deduplication and Compression Enabled

Deduplication and Compression Overhead

Deduplication algorithms break data files into contiguous segments, or compute fingerprints, used to identify duplicate segments and reduce the data footprint. This is a basic deduplication concept. The specific approach varies among system vendors, but any deduplication method consumes CPU to compute the segment fingerprints or hash keys, and it executes IO operations when performing lookups on the segment index tables. vSAN computes the fingerprints and looks for duplicated segments only when the data is being de-staged from the cache to the capacity tier. This means that under normal operations, VM writes to the write buffer in the cache SSD should incur no latency impact.

The cost of the deduplication occurs when data is de-staged from the cache to the capacity tier. It consumes a portion of CPU capabilities reserved for vSAN, and the disk operations generated by the index lookups consumes a portion of the backend IO capabilities.

Because resource consumption varies according to IO patterns, data types, etc., consult with an Dell EMC or VMware specialist before deciding whether deduplication is recommended for your application.

More information can be found in: Technical Whitepaper VMware VSAN 6.2 Space Efficiency Technologies at http://www.vmware.com/files/pdf/products/vsan/vmware-vsan-62-space-efficiency-technologies.pdf

Erasure Coding

Erasure Coding is another capacity-efficient solution for the failure tolerance method and data protection on all-flash VxRail configurations. As an alternative failure tolerance method to the data replication provided by RAID-1 mirroring, erasure codes can provide up to 50 percent more usable capacity than purely conventional RAID-1 mirroring, which drains storage space.

Erasure coding breaks up data into fragments and distributes redundant chunks of data across the system. It introduces redundancy by using data blocks and striping. To explain basically, data blocks are grouped in sets of n, and for each set of n data blocks, a set of p parity blocks exists. Together, these sets of (n + p) blocks make up a stripe. The crux is that any of the n blocks in the (n + p) stripe is enough recover the entire data on the stripe.

VXRAIL CONCEPTS AND ARCHITECTURE

In VxRail clusters, the data and parity blocks that belong to a single stripe are placed in different ESXi hosts in a cluster, providing a layer of failure tolerance for each stripe. Stripes don’t follow a one-to-one distribution model. It’s not a situation where the set of n data blocks sits on one host, and the parity set sits on another. Rather, the algorithm distributes individual blocks from the parity set among the ESXi hosts.

Erasure coding provides single-parity data protection (RAID-5) that can tolerate one failure (FTT=1) and double-parity data protection

(RAID-6) that can tolerate two failures (FTT=2). The diagrams below (62 and 63) illustrate the implementations. A single-parity stripe uses three data blocks and one parity block (3+1), and it requires a minimum of four hosts or four fault domains to ensure availability in case one of the hosts or disks fails (as in Figure 62). It represents a 30 percent storage savings over RAID-1 mirroring. Dual parity saves as much as 50 percent capacity over RAID-1. It uses four data blocks plus two parity blocks (4+2) and requires a minimum of six nodes (as in Figure 63).

Figure 62. RAID-5 (FTT=1) requires a minimum of four nodes.

Figure 63. RAID-2 (FTT=2) with 4+2 Nodes

Look at the comparison of usable capacity in the graph below (Figure 64). The erasure-code protection method increases the usable capacity up to 50 percent compared to mirroring.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 64. Erasure coding increases usable capacity up to 50 percent.

Enabling Erasure Coding

The SPBM policy Failure tolerance method (or FTM) lets administrators choose between RAID-1 (Mirroring) and RAID-5/6 (Erasure

Coding). The FTT policy (in Figure 65) determines the number of parity blocks written by the erasure code.

Figure 65. FTT policy determines the number of parity blocks written by the erasure code.

VxRail implements erasure coding at a very granular level, and it can be applied to VMDKs, making for a nuanced approach.

Configurations for VMs with write-intensive workloads

—a database log, for instance—can include a mirroring policy, while the data component can include an erasure coding.

Requirements

Erasure coding requires a minimum number of fault domains to ensure availability. (Remember that if no fault domains have been defined, an individual host becomes fault domain.)

Erasure Coding Overhead

Erasure coding saves space at the cost of performance. Computing parity blocks consumes CPU cycles and adds overhead to the network and disks, as does distributing data slices across multiple hosts. This extra activity can affect latency and overall IOPS throughput.

VXRAIL CONCEPTS AND ARCHITECTURE

The rebuild operation also adds overhead. In general, rebuild operations multiply the number of reads and network transfers used for replication. A formula is available here, too. If n refers to the number of blocks in a stripe, then the rebuild operations cost n times that of ordinary replication. For a 3+1 stripe, that means three disk reads and three network transfers for every one of conventional datareplication. The rebuild operation can also be invoked to serve read requests for currently available data.

This additional I/0 is the primary reason why only all-flash VxRail configurations use erasure coding. The rationale here is that the flash disks compensate for the extra I/O.

VXRAIL CONCEPTS AND ARCHITECTURE

SUPPORT FOR EXTERNAL NETWORK STORAGE

The vSAN presents a robust, secure, and efficient shared datastore to all nodes within a VxRail cluster. External SAN storage is typically not part of a VxRail environment. However, often a requirement exists to access external storage in order to move virtual machines and data into a VxRail environment or move data between environments or even to cloud storage. Because of the HBA requirement, Fibre Channel SAN connectivity is not possible. However, IP-based storage is ideal for this purpose, and VxRail

Appliances support both iSCSI and NFS. An important distinction is that data in the iSCSI or NFS datastore is self-contained and is not distributed to the disk groups within the VxRail cluster.

ISCSI with VxRail

iSCSI can be used to provide mobility for VMs and associated data onto and between VxRail environments. Figure 66 below shows a

VxRail environment that includes iSCSI storage in addition to the vSAN datastore. Data on the iSCSI storage is easily moved into the

VxRail vSAN environment or between VxRail environments.

Figure 66. Data Mobility into and between VxRail Environments

Existing iSCSI storage can also be used to provide additional capacity to the VxRail environment. However with the VxRail scale-up and scale-out configuration flexibility, external storage is typically not used to meet capacity requirements. iSCSI provides block-level storage using the SCSI protocol over an IP network. SCSI uses a client-server, initiator-target model where initiators issue read/write operations to target devices, and targets either return the requested read data or persistently save write data. iSCSI in a VMware environment is standard functionality. A software adapter using the NIC on an ESXi host is configured as an initiator, and targets on an external storage system present LUNs to the initiators. The external LUNs could be used by ESXi as raw device mapping (RPM) devices, however usually, the use case is for VxRail to configure them as VMFS datastores. (Refer to vSphere documentation for more information: Using ESXi with iSCSI SAN.) iSCSI configuration is performed using the vSphere Web Client. The steps involve creating a port group on the VDS, creating a

VMkernal Network Adapter and associating it with the port group, and assigning an IP address. Then, from the vCenter Manage

Storage Adapters view, the Add iSCSI Software Adapter dialog is used to create the software adapter. The last step is to bind the iSCSI software adapter with VMkernel adapter. Once this is complete, iSCSI targets and LUNs can be discovered and used to create new datastores and map them to the hosts in the cluster. (Refer to the VMware documentation for more details.) iSCSI works best in a network environment that provides consistent and predictable performance, and a separate VLAN is usually implemented. iSCSI network requirements should be considered when planning the network requirements for VxRail environment to make sure connectivity to the external iSCSI storage system exists, and the additional network traffic will not impact other applications.

NFS with VxRail

NFS is a network filesystem that provides file-level storage using the NFS protocol over an IP network. It can work in use cases similar to iSCSI

—the difference being that NFS devices are presented as file systems rather than block devices. Figure 67 below shows an

NFS file system that has been exported from a network-attached server and mounted by the ESXi nodes in the VxRail environment.

This enables data mobility into and between VxRail environments as well as enabling additional storage capacity.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 67. Network Attached File System with VxRail

The external NFS server can be an open system host, typically Unix or Linux, or a specially built appliance. The NFS server takes physical storage and creates a file system. The file system is exported and client systems, in this example ESXi hosts in a VxRail

Appliance, mount the file system and access it over the IP network.

Similar to iSCSI, NFS is a standard vSphere feature and is configured using the vCenter Web client. This is done in the Hosts and

Clusters view under Related Objects and the New Datastore dialog. Select NFS as datastore type, the NFS version, the name of the datastore, the IP address or hostname of the NFS server that exported the filesystem, and the host that will mount it. The NFS filesystem will appear like the vSAN datastore. VMs, templates, OVA files, and other storage object can be easily moved between the

NFS filesystem and the vSAN datastore using vMotion.

As with iSCSI, NFS works best in network environments that provide consistent and predictable performance. The network requirements for NFS should be considered when initially planning the network requirements for VxRail environment.

VXRAIL CONCEPTS AND ARCHITECTURE

INTEGRATED SOLUTIONS

VMware Horizon

VMware Hori zon is VMware’s VDI and desktop-management environment. Horizon provisions user desktops using a flexible and secure delivery model. The desktop environments are accessed by the user from almost any device, including mobile devices, with the security and resiliency of the datacenter. Because the application software and data components reside in the datacenter, traditional security, backup, and disaster recovery approaches may be applied. If a user's device is lost or the hardware fails, the recovery is straight forward. The user simply restores the environment by logging in using another device. With no data saved on the user's device, if the device is lost or stolen, there is much less chance that critical data could be retrieved and compromised. Figure 68 below shows how Horizon View encapsulates the OS, applications, profiles and user data into isolated layers and dynamically assembles desktops on demand to provide users with a personalized view of their individual environments.

Figure 68. Highly Available and Secure Desktops

Availability and security, along with ease of management and support, are compelling reasons for moving from traditional physical desktops and laptops to VDI.

VMware Horizon is a comprehensive desktop management environment that runs in a vSphere environment. The environment is managed through vCenter centralized management and can leverage advanced capabilities including, Snapshots, vMotion, Dynamic

Resource Scheduler (DRS), and vSAN storage.

The user’s desktop environment runs as a View Desktop VM on an ESXi server, and is accessed via the View Client that uses either

RDP or PCoIP protocols. The View Client can be an application running on a physical desktop, laptop, mobile device, or a web browser using the View Portal. The user’s desktop environment can be either a dedicated VM or a floating VM (a VM assigned from a pool when the user logs in). Using the optional View Composer, rather than full images, linked clones can reduce the disk space required.

Horizon View includes additional components used to manage the connection, provisioning the environment, authenticate users, and other applications and services.

VMware Horizon with VxRail

The VxRail Appliance is a self-contained compute, storage, and vSphere virtualization and management environment that is ideally suited for VMware Horizon. VxRail accelerates the Horizon infrastructure deployment, and an environment can be up in running in hours rather than days.

VxRail hyper-converged infrastructure is available in configurations that support hundreds to thousands of virtual desktops. The number of desktops supported is based on the user-workload profile.

Dell EMC has developed tools which provide the ability to model the number of VDI environments and the expected workload profiles to determine appropriate configuration that will meet the immediate and longer term requirements. As demand increases, VxRail nondisruptively scales-up by adding additional appliances and nodes while providing the users with expected performance and consistent user experience.

VXRAIL CONCEPTS AND ARCHITECTURE

When deploying Horizon on VxRail Appliances, there are two general approaches: dedicating the VxRail environment to VDI or mixing

VDI with other workloads. Horizon Editions or Horizon Add-on Editions are offered exclusively for use with VxRail. VMware or Dell EMC sales representatives can provide more details for the best customer-specific option.

In summary, VxRail with VMware Horizon allows an organization to quickly implement Desktops as a Service (DaaS) and overcome the traditional CAPEX barriers of desktop virtualization. The environment can start small and easily scale up as needed. This lowers the initial startup investment. VxRail hyper converged infrastructure is not only quick to setup, its integrated compute, storage, virtualization, and single vendor support model eliminate the complexity of traditional infrastructure

Native Hybrid Cloud (NHC) with Pivotal Cloud Foundry

In today’s digital world, applications are the face of a company and user experience is paramount. This means applications must be always available and accessible from anywhere, on any device. Applications also have to respond to the rapidly changing dynamics of the business, and this means new applications need to be to be brought online in days or weeks rather than months or years, and release cycles are ongoing. Updates are made in real time as applications evolve based on deep analytics that continually improve business outcome. The key is agility and speed to innovation, and the best way to achieve this is to architect the solutions natively to run in the cloud as PaaS services. Native-cloud applications must also balance the need to move rapidly with the need for stability, availability, and durability.

The best platform to build, deploy, and manage native-cloud PaaS services is Pivotal Cloud Foundry (PCF). PCF provides an enhanced development environment that maximizes productivity, along with enterprise-grade security and availability. Once developed,

PCF PaaS applications provide IT Operations with full visibility and control through built-in monitoring and reporting. The Analytic

Insights Module helps gather, analyze and reveal actionable insights to achieve the best business outcome. Applications built on PCF are portable and can run on any private or public cloud providing scale and elasticity.

PCF runs on many different public and private cloud platforms including vBlock, VxRack, and, VxRail. Cloud Foundry is an open-source cloud computing platform originally developed in house at VMware. It is now owned by Pivotal Software, a joint venture made up of

VMware, EMC, General Electric, and part of Dell Technologies. The fastest way to get up and going with a Cloud Foundry solution is with Native Hybrid Cloud,

Dell EMC’s PCF implementation, on VxRail. This is a complete turnkey platform providing the fastest path to deploying Cloud Foundry. It is built on vSphere, and the VxRail hyper-converged infrastructure with vSAN technology. The solution is engineered to combine self-service cloud-native application development with data analytics into a single hybrid-cloud platform that can be deployed in a day, rather than the months that it would take to build your own. Native Hybrid Cloud on VxRail is sustained as one product and supported end-to-end by Dell EMC. Figure 69 below shows the Native Hybrid Cloud on VxRail with Pivotal Cloud Foundry as an integrated stack.

The primary components of the solution are:



Pivotal Cloud Foundry

Figure 69. Native Hybrid Cloud

VXRAIL CONCEPTS AND ARCHITECTURE



vSphere



VxRail the hyper-converged infrastructure with vSAN



NHC M&R and Install tools.



End-to-end support by Dell EMC

This VxRail Native Hybrid Cloud is ideal for vSphere-invested environments that want to continue that investment from an OpEx perspective. Native Hybrid Cloud solutions are also available on the VxRack systems with Neutrino nodes for larger scale. Both offer the benefits of an integrated solution and seamless support. Native Hybrid Cloud provides agility and speed to innovation and reduces the risk associated with deploying and managing cloud native applications. For more information please visit: http://www.emc.com/enus/cloud/hybrid-cloud-computing/solutions.htm#tab-3.

VxRail VM Replication

Several options are available for replicating virtual machines for data protection and disaster recovery in VxRail clusters. Among them and which are integrated into the VMware software stack are VMware vSphere Replication (VR), and RecoverPoint for Virtual Machines

(RP4VM), which is built on enterprise proven Dell EMC RecoverPoint technology.

When choosing the right solution, Recovery Point Objectives (RPO) is an important consideration. RPO defines the maximum acceptable age of data recovered from a replicated copy as a result of a data loss issue. For example, if a virtual machine is deleted and the RPO for the virtual machine is 24 hours, a recovered copy of the virtual machine should contain all data except for any changes that occurred in the last 24 hours. Depending on the technology, RPOs as low as a few seconds or minutes can be configured.

Another consideration is the number of recovery points to retain. When configuring replication for a virtual machine, an administrator has the option to enable the retention of multiple recovery points (point-in-time instances). This can be useful when an issue is discovered several hours, or even a few days, after it occurred. For example, a replicated virtual machine with a four-hour RPO contracts a virus, but the virus is not discovered until six hours after infestation. As a result, the virus has been replicated to the target location. With multiple recovery points, the virtual machine can be recovered and then reverted to a recovery point retained before the virus issue occurred.

VMware vSphere Replication

VMware vSphere Replication (VR) is a hypervisor-based, asynchronous replication solution that is fully integrated with VMware vCenter

Server. It uses a proprietary replication engine developed by VMware and is included with VMware vSphere Essentials Plus Kit and higher editions of VMware vSphere. While VR works well with vSAN storage in a VxRail hyper-converged environment, it is completely independent of the underlying storage and allows for replication between heterogeneous storage types. This is useful when a VxRail

Appliance is part of a larger virtualization environment that includes SAN or other storage types. VSR provides data protection locally within the same vCenter environment as well as disaster recovery and avoidance to another vCenter site. It also supports replication to

Service Provider clouds such as vCloud Air. Figure 70 below shows VR replication between two VxRail sites.

Figure 70. VMware vSphere Replication with VxRail

VXRAIL CONCEPTS AND ARCHITECTURE

In this example, several VMs are replicated to a remote site with a RPO of 15 minutes. The remote site maintains multiple VM images, allowing roll back to different point-in time.

The VR components that transmit replicated data are built into vSphere and uses Secure Sockets Layer (SSL) connection. A best practice is to isolate network traffic to improve performance and security. VR also includes one or more prebuilt Linux-based vSphere

Replication vApps. The first virtual appliance is referred to as the vSphere Replication Management server. It receives replicated data, manages authentication, and maintains mappings between the source virtual machines and the replicas at the target location. Each appliance requires 18GB of VMDK storage, 4GB of memory, and either two or four virtual CPUs.

VR configuration includes specifying the Recovery Point Objectives (RPO) within a range of 15 minutes to 24 hours as well as the number of point-in-time time images to maintain. This is all done from within vSphere Web Client using a simple wizard. Once replication has been configured for a virtual machine, vSphere Replication begins the initial full synchronization of the source virtual machine to the target location. The time required to complete this initial synchronization can vary depending on the amount of data that must be replicated and the amount of available network bandwidth. After the initial full synchronization, only changed data is transmitted in each replication cycle, minimizing the network bandwidth requirements.

The replicated data is first written to a redo log. After all changes for the current replication cycle have been received and written to the redo log, the data in the redo log is merged into the base image. This process ensures a consistent and recoverable VM image is available at all times. vSphere Replication delivers flexible, reliable and cost-efficient replication for data protection and disaster recovery. It is seamlessly integrated within the VMware product stack for simple deployment, configuration, and management.

Dell EMC RecoverPoint for Virtual Machines

RecoverPoint for Virtual Machines (RP4VM) is based on the RecoverPoint continuous data protection technologies that have been proven in enterprise environments for over ten years with over 350 million run hours and an entire Exabyte of data protected. Like VRS,

RecoverPoint for VMs enables customers to replicate virtual machines simply and is configured and managed from within vSphere Web

Client using the RecoverPoint plug-in.

While similar in concept to VSR, RP4VM has a number of unique capabilities including the ability to configure an RPO as low as zero seconds, as well as concurrent local and remote replication, and multi-site 2:1 and 1:2 configurations.

RecoverPoint for VM includes a RecoverPoint Virtual Appliance (vRPA) that manages all aspects of data replication. Two-to-eight vRPAs are grouped as a cluster. For local replication, a single cluster would be configured. For remote replication, a cluster is configured at both the local and remote sites. A RecoverPoint Splitter is also installed on each ESXi server. The splitter takes each write and sends it to both the VMDK and to the vRPA. Management of RPVM is all done from within vCenter using the RecoverPoint for

VMs plugin.

The source of replication is the virtual machine and associated application data and is referred to as the production copy. RPVM performs continuous data replication of writes to the production copy. Each write is split and sent to both the VMDK and to a journal.

The journal provides DVR-like roll back and is used to create a local copy that reflects any point in time. The local copy can be used to recover from logical errors and data corruption. Optionally, RPVM can be configured to synchronously or asynchronously replicate to a remote vRPA cluster. The local and remote vRPA clusters communicate over a WAN connection and compression and de-duplication provides optimization and reduces bandwidth consumption.

Figure 71 below shows an environment with both local and remote data protection and how writes are split, journaled, and used to create point-in-time images.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 71. Continuous Local and Remote Protection

Other RPVM features include automated discovery, provisioning and orchestration of DR workflows, including test, and failover and failback of a single VM or multiple VMs using consistency groups.

A license Starter Pack is included with each VxRail Appliance. Additional licenses can be purchased as needed.

VxRail Replication Use Case

Both VSR and RPVM provide data protection and disaster-recovery capabilities. Both are software-only solutions that are embedded in the hypervisor, use vApps for control, and are managed from vCenter. Which to use depends on the use case.

Local replication to other appliances, remote replication to other VxRail clusters, or non-VxRail vSphere clusters may be configured.

Remote replication may be used to provide DR to ROBO sites. Other use cases include VM migration from other vCenter environment into and between VxRail environments.

For basic replication that is fully integrated and easy to manage using VMware vCenter, VSR provides these capabilities at no additional cost. If an RPO of less than five minutes, only RPVM can provide continuous data replication with DVR-like playback. RPVM also supports more flexible deployment options including concurrent local and remote replication and multiple sites in a 2:1 or 1:2 configuration.

Regardless of the replication choice, solution sizing should include the additional storage capacity required and the overhead of replication vApps.

Storage Tiering and File Support with CloudArray

Dell EMC CloudArray, Dell EMC

’s cloud storage gateway, is integrated into VxRail and it seamlessly extends the appliance to public and private clouds to securely expand managed storage capacity. Cloud-storage gateways make it possible to take advantage of storage services from both public and private cloud storage providers while maintaining predictable performance behavior. Dell EMC

CloudArray is accessed through VxRail Manager and provides an additional 10TB of on-demand cloud storage per appliance. Dell EMC

CloudArray currently provides connections (APIs) to over 20 different public and private clouds including Dell EMC ViPR, VMware vCloud Air, Rackspace, Amazon Web Services, Google Cloud, Dell EMC Atmos, and Openstack. VxRail CloudArray can provide an elegant, seamless solution for cost-efficient cold (inactive) data storage or an easily accessible online archive with predictable performance behavior.

VxRail deploys CloudArray as a virtual appliance, a preconfigured, ready-to-run VM packaged with an operating system and a software application. Self-contained virtual appliances make it simpler to acquire, deploy, and manage applications. The CloudArray virtual appliance is essentially a VM already installed with and running the Dell EMC CloudArray software application. The communication between the VxRail VMs and the CloudArray VM takes place through the VM IP network. An iSCSI initiator is configured on the VM’s

VXRAIL CONCEPTS AND ARCHITECTURE

guest OS to connect it to the CloudArray VM, and the IP address of the CloudArray VM is defined as the iSCSI target. Diagram 72 below illustrates the implementation.

Figure 72. CloudArray Communication

When using VxRail and CloudArray for cloud tiering, virtual disks (vdisks) are first created in the vSAN datastore for the CloudArray virtual appliance to use as cache sources. CloudArray identifies these vdisk devices as cache sources and places them in pools, and the cache sources then allocate the capacity into different-sized spaces, or cache areas.

For the VxRail Appliance, CloudArray creates volumes using specific volume-provisioning definitions associated with the cache area.

These definitions determine whether the volume accesses capacity from a cloud service or remains local (cloudless). Typically, local provisioning requires large cache areas that can store 100 percent of the volume capacity locally. Large cache areas accommodate frequently accessed volumes. Less-active volumes are generally provisioned using small cache areas and leverage a cloud provider for capacity.

Observe in the illustration below (Figure 74) that Vol1 requires 10GB of capacity from Cache1, which can provide up to 600GB of capacity. On the other hand, Vol2 requires 100GB of capacity from Cache2, which is allocated from a cache area that provides only

25GB of capacity. Regardless of the cache area size, the cache always maintains the most recently accessed data, and the less frequently accessed data can be tiered to a cloud.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 73. CloudArray Cache Sources

CloudArray can also create and schedule in-cloud snapshots, which are extremely space efficient and can be controlled via age-based retention controls. A granular bandwidth scheduler helps optimize WAN utilization by enabling the scheduling and bandwidth control used by CloudArray. Local caching naturally reduces bandwidth consumption and data latency, and only changed data blocks are sent to the cloud after the initial data is delivered.

CloudArray also provides a multi-layered AES 256-bit encryption. Both data and metadata are encrypted separately, with two different sets of keys. Furthermore, the keys themselves are password protected.

Figure 74. CloudArray Local and Cloud Storage

CloudArray software also provides local file support for vSphere using VxRail compute to run the VMs servicing the file stores.

Supported file protocols include CIFS (SMB/SMB2/SMB3) and NFS (Versions 3 and 4).

In conclusion, CloudArray offers VxRail environments a valuable set of extended services to make cloud tiering simple, secure, reliable, and efficient. For more information about CloudArray, refer to Dell EMC CloudArray Product Description and Administrator Guides:

 https://www.emc.com/collateral/guide/h13456-cloudarray-pdg.pdf

 http://uk.emc.com/collateral/TechnicalDocument/docu60786.pdf

Integrated Backup and Recovery with vSphere Data Protection (VDP)

VxRail Appliances interoperate with vSphere Data Protection (VDP) for extended backup and recovery services. VDP is deployed as a

Linux-based virtual appliance and includes up to 8TB of backup virtual disks per ESXi host. VDP protects every application or VM on the VxRail Appliance. It features the familiar vCenter Server interface and is powered by Dell EMC Avamar with built-in enterprise deduplication to reduce network bandwidth and shrink backup windows. VDP leverages vCenter management for one-step recovery with verification, enabling 30 percent-faster backups compared to disk backup. VDP provides agentless backup and recovery for VMs running vSAN datastores. VDP’s deduplication uses a variable-length segment algorithm that reduces consumption in backup storage.

Backup data can also be moved offsite using replication.

VDP backs up VMs without running any services within the VM itself. APIs allow VDP to connect to the ESXi host running the VM and to take a snapshot via a process similar to vSAN

’s standard snapshot technology. The VDP snapshot is a static, read-only, point-in-time reference that non-disruptively captures virtual-disk data and VM-configuration information. The snapshot information is then copied to backup media, and VDP tracks changes to disk sectors using changed-block-tracking (CBT).

In addition, VDP has the ability to reduce bandwidth consumption by using SCSI Hot-Add for backup data transmission. VDP attaches a vdisk to the backup storage device the same way the vdisk would attach to a VM. As long as the ESXi host of the VM being backed up has access to the backup storage device, VDP does not use the network. (See the diagram in Figure 75 below.) If the ESXi host cannot

VXRAIL CONCEPTS AND ARCHITECTURE

access the backup storage device, VDP sends the encrypted snapshot data across the network using an incremental transmission to maintain low bandwidth.

Figure 75. vSphere Data Protection

VXRAIL CONCEPTS AND ARCHITECTURE

VXRAIL SERIES USE CASES

The broad Dell EMC VxRail Appliances product portfolio offers a range of platforms designed to support multiple use cases. While each

VxRail Series is designed with a particular use case in mind, there may be good reason to use each VxRail Series for other use cases as well.

Figure 76. Purpose built nodes for multiple use cases

Dell EMC VxRail Appliance portfolio innovation drives use-case innovation so businesses can thrive. The VxRail Appliance will evolve and quickly integrate the latest technologies and capabilities to make it the most flexible HCIA platform on the market while continuously offering industry leading management via existing VMware tools, single-node scaling and storage-capacity expansion, and comprehensive data-protection options.

This section further details use cases that highlight specific customer solution implementation that benefit from the simplicity and business value of the VxRail Appliance.

Figure 77. Broad Range of Use Cases

Use Case: Platform as a Service (PaaS)

With the demands of today’s digital world, applications must be always available and accessible from anywhere, on any device. These applications must respond to the rapidly changing dynamics of the business where new applications are brought online in days or weeks rather than months or years. These requirements are best achieved when applications are architected to run natively in the cloud as PaaS services. These PaaS services can be developed and deployed in public or private clouds, but many companies have determined the best approach is a hybrid cloud, where applications are developed and maintained locally and deployed on private cloud infrastructure and leveraging the elastic capacity of public cloud providers.

VXRAIL CONCEPTS AND ARCHITECTURE

A PaaS software stack includes many components. You can choose each component and build your own stack or deploy a turnkey platform such as Pivotal Cloud Foundry. Regardless of the choice, PaaS needs infrastructure to run, and for private or hybrid-cloud implementations, VxRail, build on vSphere and vSAN technologies, provides the fastest path to standing up a PaaS environment.

VxRail presents a pool of compute, memory, and storage resources for the PaaS applications with flexibility to choice the right balance of resources for the cloud-native application. The infrastructure can be set up in a day and ready to deploy services immediately. As workloads increase, the resource pool can grow an appliance node at a time.

As illustrated in the diagram below, the fastest path to offering PaaS Services is the Native Hybrid Cloud solution using VxRail

Appliances where the PaaS layer is provided by Pivotal Cloud Foundry, and VxRail with vSphere and vSAN technologies provide the

IaaS layer, all as a turnkey solution with single solution support.

Figure 78. Native Hybrid Cloud with VxRail

Use Case: Hybrid Cloud

The decision to deploy services in private verses public cloud depend on a number of different factors but many companies have determined that a hybrid cloud provides agility and control they need and allows them to meet strict security and regulatory requirements, and at the same time benefit from the elasticity and scale that that public clouds provide.

The foundation for a hybrid cloud is an on-premise private cloud infrastructure and VxRail provides predictable pay-as-you-grow deployment of cloud infrastructure. With the flexible compute, memory, and storage options, the pooled resources right balance of system resources VxRail appliances can be stood up in less than a day, and easily scale up and out as workloads grow. VxRail, with its familiar and pervasive vSphere stack, is the ideal environment to deploy services to the cloud.

Automation is also a key component of the hybrid cloud, and VMware vRealize Automation

provides policy-based governance and logical application modeling to ensure cloud services are delivered at the right size and service level. Full lifecycle management assures resources are maintained at peak operating efficiency and release automation allows application deployments to be kept insynch through the development and deployment process.

VXRAIL CONCEPTS AND ARCHITECTURE

Figure 79. vRealize Automation for the hybrid cloud

Use Case: Analytics and Collaboration

VxRail provides support for data analytics and collaboration use cases on proven vSphere-based hyper-converged infrastructure.

These use cases often have large data sets. VxRail offers dense storage configurations with up to 48TB of RAW capacity per node and over 3PB of RAW capacity per cluster. With one-day infrastructure deployment and the ability to purchase only what is needed and scale up and out as capacity requirements grow, VxRail is the ideal platform for Analytics and Collaboration.

Figure 80. Analytics and Collaboration Use Cases

Use Case: Server Workloads

Enterprise workloads such databases and applications supporting the business that traditionally run on virtualized or physical servers most often have stringent requirements for data protection and high availability. Only Dell EMC, with VxRail, can guarantee uptime and offers the breadth of industry leading data protection & HA features to meet any RPO/RTO.

Server workloads can differ greatly and VxRail offers node choices in the number of CPU cores, speed of process, memory, and storage to meet the application requirements and a cluster can have a mix nodes to align with the workload. Server environments often start small and grow and VxRail offers the flexibility to scale up and scale out to meet growing workloads. A single cluster can grow to

64 nodes with the granularity to grow a single node at a time.

Use Case: End User Computing Services (EUC)

End User Computing pertains to how users, with multiple devices, are able to access their applications and data from anywhere at any time. This is a proven strategy, and enterprises large and small are achieving the benefits of an effective ECS strategy using Virtual

VXRAIL CONCEPTS AND ARCHITECTURE

Desktop Infrastructure (VDI) technologies that includes server virtualization, high performance storage for desktop images and data, and low latency network for connectivity.

EUC infrastructure can be combined with other workloads but is often deployed in a standalone environment. Either way, the Dell EMC

VxRail Appliance is the perfect platform to deploy EUC. They are the easiest, fastest, most affordable way to implement a VDI infrastructure. Rapidly deploy an appliance that integrates market-leading compute, storage, virtualization, and management software from Dell EMC and VMware to set up a VDI infrastructure in minutes. Flexible configuration options and modular scalability ensure that compute and capacity are always available, whether deploying hundreds or thousands of virtual desktops. The VxRail Appliance’s highly redundant architecture, integrated Dell EMC data-protection software, and non-disruptive upgrades create certainty that virtual desktops will always be available to end users and that the user experience will always exceed expectations. Dell EMC VxRail

Appliances are a family of hyper-converged infrastructure (HCI) appliances that include a full suite of industry-leading data services, including replication, backup, and recovery for data protection. Built on the foundation of VMware Hyper-Converged Software and managed through the familiar VMware vCenter interface, VxRail Appliances provide customers with a familiar experience that also allows them to take advantage of the hallmark benefits of Dell EMC

—increased agility, simplified operations, and lower risk.

VxRail Advantages for VDI



Quick and easy automated deployment with power-on to VM creation in minutes and easy, ongoing VM management



Scalability from hundreds of virtual desktops per appliance, and thousands of desktops in a fully-populated VxRail cluster



One-click, non-disruptive patches and upgrades



Application uptime ensured through highly available VMware vSAN



Automated operational and disaster-recovery orchestration for VMs, including local and remote replication and continuous data protection with granular recovery to any point in time

VxRail Appliances enable customers to reduce VDI footprints, saving power and infrastructure costs while minimizing administrative burdens and lowering operational costs. The modular, just-in-time purchase approach enables predictable evolution with a repeatable, simple, and agile means to scale on demand. VxRail Appliances can host virtual desktops from VMware, Citrix, and other VDI vendors.

Businesses can be confident that VxRail Appliances will meet the performance and capacity demands associated with desktop growth as well as application and user demands through continuous hardware and software evolution. VxRail Appliances seamlessly integrate new enterprise class x86 and storage technologies, and they non-disruptively update to the latest VMware software to ensure that the

VDI deployment can continuously modernize to meet business demands.

Meeting the Virtualization Challenge for Federal Agencies

Business Challenge

The IT challenges facing today’s federal government organizations are much like those of their corporate counterparts: deadlines and budgets shrink while expectations grow. They need to provide security and the freedom and flexibility to support a mobile workforce.

However, federal agencies also face the added pressures of public oversight. IT purchases may be subject to strict procurement guidelines, require more than the typical due diligence in planning and may take more time for purchase approvals. In one study of federal IT professionals, more than half (54 percent) said they do not believe that their agency is able to acquire new IT resources in a timely manner. This is a challenge, especially in light of the fact that many federal agencies are vulnerable to the problems and inefficiencies of aging IT systems and infrastructures. The same survey noted that 77 percent felt that their agencies needed a more flexible IT infrastructure.

Business Solution

For increasing numbers of federal agencies, the answer to the challenge is IT resource virtualization. A virtual desktop infrastructure puts resources precisely where they are needed and in the strength they are needed at a moment’s notice. Virtualized IT infrastructures are in place in most large organizations today. But until the recent advent of HCI technology, they have been beyond the reach of smaller federal agencies or departments within large federal organizations. With Dell EMC VxRail Appliances, federal organizations can take advantage of a “just-in-time” approach to deployment and expansion. An organization can start with a single appliance and then build out an IT infrastructure over time. This can help expedite the procurement process by keeping incremental purchase amounts for technology below discretionary federal agency spending limits. It can also reduce the need for overprovisioning and facilitate the creation of a master configuration that can be replicated in other departments within the organization.

VXRAIL CONCEPTS AND ARCHITECTURE

VxRail Appliances make federal agencies more confident in their IT infrastructure because they provide a pre-configured, pre-tested solution jointly developed by Dell EMC and VMware, trusted vendors by organizations around the world, and they are backed by a single point of 24/7 global support for all appliance hardware and software. With VxRail Appliances, businesses can be confident that the virtual infrastructure will work today and will lead them along the path to more innovative technologies, from cloud computing to the software-defined data center (SDDC).

Use Case: Simplifying the Distributed Enterprise Environment

Distributed Enterprises usually have a central IT staff that creates the overall business network architecture for the enterprise, and also have many remote offices that are essential to running the business, normally with limited on-site technical staff. However, the infrastructure and data at these distributed locations is mission critical. Typical important operations found in distributed enterprises are warehousing and distribution, manufacturing of the company's core products, and mobile or remote life-saving operations like health clinics. Support responsibilities for these remote operations usually fall to the central IT staff. According to Enterprise Strategy Group

(ESG) in their 2015 research report Remote Office/Branch Office Technology Trends, 72 percent of organizations intend to increase spending on remote office IT infrastructure. In addition to the above challenges, footprint is an issue because remote locations, unlike data centers, do not have the dedicated space, power, or cooling capabilities necessary for multiple servers running multiple applications. This means remote organizations are much more sensitive to server sprawl. While some organizations may look to the cloud to reduce server sprawl and centralize operations, in many cases that is not feasible. This is because offices either are in remote locations with limited Internet service or have minimal WAN bandwidth and redundancy available. So issues such as latency and availability become limiting factors. Dell EMC VxRail Appliances are ideal for consolidating multiple applications in a remote location onto a single cost optimized and highly available platform that is easy to deploy and manage.

Dell EMC VxRail Appliances that integrate compute, storage, virtualization, and management software from Dell EMC and VMware are the optimal endpoints for the distributed enterprise. As an integral solution in the Dell EMC converged infrastructure portfolio, VxRail

Appliances can be monitored with Vision Intelligent Operations, enabling IT to have visibility across the distributed solution from the same single-pane-of-glass console used to manage the data center infrastructure. The VxRail Appliance enables customers to consolidate multiple remote office applications onto a single appliance. VMware vSAN software integrated with flash or hybrid storage ensures the highest possible performance since vSAN is embedded in the hypervisor and eliminates many data path bottlenecks.

Simple deployment enables customers to be up and running in 15 minutes. The local team only needs to plug in the appliance and power it up. All other configuration can be done remotely. In addition, the VxRail Appliance is the only HCI appliance on the market offering Quality of Service (QoS) functionality that eliminates “noisy neighbors.” This functionality makes it certain that multiple applications can be hosted on the same appliance or in the same cluster without performance impact.

VxRail Appliance Advantages for Distributed Enterprises



Cost-optimized entry point for remote office branch office (ROBO)



Tailored compute and capacity deployment for each remote location



Simple, standard set-up, reducing IT skills needed at remote locations



Part of a complete portfolio of converged infrastructure core-to-edge solutions



Backup locally at the remote office or over the WAN to central data centers with RecoverPoint for VMs



Management and visibility across the distributed enterprise with VMware tools and Vision software

Meeting the Distributed Enterprise Challenge for State and Local Agencies

Business Challenge

For state and local agencies, the promises of new technology come with unique new challenges as well. New applications, including those for remote and mobile computing, for example, can boost user productivity, but they present performance and data-storage demands for aging IT infrastructures that their original planners could not have foreseen. State and local systems are barely able to keep up with the refresh cycles of their various hardware and software components, much less adjust to today’s demands for tightened service level agreements, shorter project deadlines, and shrinking budgets. Pressured to keep costs low, agencies have difficulty justifying specialized IT technicians or even new real estate to support an upgrade in IT infrastructure.

VXRAIL CONCEPTS AND ARCHITECTURE

Business Solution

For a fast-growing segment of state and local agencies, a hyper-converged appliance is an effective solution to the problems of high expectations and small budgets. Leveraging VxRail Appliances reduces cost by eliminating conflicting system-refresh cycles and redundant software and the need for specialized IT technicians. VxRail Appliances provide the ability to put compute resources where they are most needed at any given time, saving the cost of over-provisioning IT systems and building out new office space for larger servers, storage, or networking gear. With the emergence of VxRail Appliances, the benefits of a Software-Defined Data Center

(SDDC) are within the reach of state and local agencies.

With conventional IT systems, deployment can take months, to plan, procure, install, configure, provision and test. And it can require the services of technicians skilled in servers, storage, networking, and applications. The more time it takes for deployment, the higher the cost and the more likely the project will be stopped in its tracks or diminished in scope by budget-conscious regulators. VxRail

Appliances avoid these pitfalls because they are totally self-contained and thoroughly tested by Dell EMC before they are shipped.

Wizard-based automation helps non-technical staff set up pools of virtual machines for users. Once this setup is complete, it takes just

15 minutes from power-on to creation of a new virtual machine. Expansion is a simple matter of plugging in a new node or adding another appliance. New nodes are hot swappable, so the appliance does not have to be powered down and no new software is required to grow your infrastructure. In addition, VxRail Appliances have a system architecture that is predictable and repeatable, new versions of a master configuration can be installed into other offices without new testing or troubleshooting.

VXRAIL CONCEPTS AND ARCHITECTURE

PRODUCT INFORMATION

For documentation, release notes, software updates, or for information about Dell EMC products, licensing, and service, go to the Dell

EMC Online Support site (registration required) at: https://support.emc.com.

Product Support

Single source, 24X7 global support is provided for VxRail Appliance hardware and software via phone, chat, or instant message.

Support also includes access to online support tools and documentation, rapid on-site parts delivery and replacement, access to new software versions, assistance with operating environment updates, and remote monitoring, diagnostics and repair with EMC Secure

Remote Services (ESRS).

Dell EMC Professional Services for VxRail Appliances

Dell EMC offers installation and implementation services to ensure smooth and rapid integration of VxRail Appliances into customer networks. The standard service, optimal for a single appliance, provides an expert on site to perform a pre-installation checklist with the data-center team, confirm the network and Top of Rack (TOR) switch settings, conduct site validation, rack and cable, configure, and initialize the appliance. Finally, an on-site Dell EMC service technician will configure EMC Secure Remote Services (ESRS) and conduct a brief functional overview on essential VxRail Appliance administrative tasks. A custom version of this installation and implementation service is available for larger-scale VxRail Appliance deployments, including those with multiple appliances or clustered environments. Also offered is VxRail Appliance extended service, which is delivered remotely and provides an expert service technician to rapidly implement VxRail Appliance pre-loaded data services (RecoverPoint for Virtual Machines, vSphere Data Protection, and

CloudArray).

Customer Upgradeable Software

VxRail Appliance software is customer upgradeable via a fully automated and validated process as of VxRail 4.0 software. The software upgrade is initiated via download from VxRail Manager, and it automatically downloads all software ready to be updated including VxRail Manager VM, vCenter Server and PSC, ESXi hosts, and ESRS. The automated process consists of four steps including download of the VxRail software, a readiness check, the actual update of the software, and finally, validation and upgrade post checks. The final validation step ensures the upgrade was successful, and the VxRail Appliance is fully functional at the new, upgraded version of software. Figure 81 below shows the four automated steps of a customer executed VxRail Appliance software upgrade. Step 3 is performed one node at a time, where the ESXi host is placed in maintenance mode, and using vMotion, the VMs are moved to other nodes making the upgrade process non-disruptive. To do this automatically vSphere Enterprise Edition Plus is required.

If the VxRail appliance is not currently running VxRail 3.5 or using vSphere Standard Edition license, services are required to perform the upgrade. (It is best to verify with Dell EMC services that an environment meets the requirements prior to an upgrade.)

Figure 81. Automated process steps for customer-executable VxRail Appliance software upgrade.

VXRAIL CONCEPTS AND ARCHITECTURE vSphere Ordering Information

VxRail Appliance allows customers to use any existing eligible vSphere licenses with their VxRail, or the licenses can be purchased with a VxRail

. This VxRail vSphere license independent model (also called “bring your own” or BYO vSphere License model) allows customers to leverage a wide variety of vSphere licenses they may have already purchased.

Several vSphere license editions are supported with VxRail including Enterprise+, Standard, and ROBO editions (vSphere Enterprise is also supported, but is no longer available from VMware). Also supported are vSphere licenses from Horizon bundles or add-ons when the appliance is dedicated to VDI.

If vSphere licenses need to be purchased, they should be ordered through Dell EMC

, the customer’s preferred VMware channel partner, or from VMware directly. Licenses acquired through VMware ELA, VMware partners, or Dell EMC will receive single-call support from Dell EMC.

Figure 82. VxRail 4.0 Licensing Details

(Note

—The vCenter license included with VxRail is for vCenter deployed on VxRail and is not transferrable to another external server.)

When determining the best vSphere license to use with the VxRail Appliance, a key consideration is the effect of VxRail functionality.

DRS, a significant vSphere feature described earlier in this TechBook, provides the greatest amount of functional variance to VxRail clusters. Customers should consider the degree of automation that DRS provides to determine if the vSphere license they desire includes this functionality.

VXRAIL CONCEPTS AND ARCHITECTURE

VSPHERE EDITIONS & PACKAGES VSPHERE EDITION FUNCTIONAL LEVEL

vSphere Enterprise Plus vSphere Enterprise vSphere Standard

Horizon Enterprise

Horizon Advanced

Horizon Standard vCloud Suite

ENT+

STD vSphere ROBO Advanced (Q3) STD* (Additional Features, no

DRS) vSphere ROBO Standard (Q3) STD vSphere Desktop (Q3) vSphere with Operations

Management

Enterprise Plus (VSOM)

ENT+, virtual desktop only

ENT+

ENT+, virtual desktop only

ENT+

VSPHERE LICENSE KEY INPUT UNIT

CPU

VM (Qty 25)

User (Qty 100)

CPU

User (Qty 10 or 100)

CPU

Reklam

DELL EMC VXRAIL

APPLIANCE

Hyper-Converged Infrastructure Appliance from

Dell EMC

®

and VMware

®

ABSTRACT

Table of Contents

PREFACE

This Dell EMC TechBook provides a thorough conceptual and architectural review of the Dell EMC VxRailTM Appliance. It reviews current trends in the industry that are driving adoption of converged infrastructure and highlights the pivotal role of

VxRail in today’s modern data center.

Audience

Related Resources and Documentation

Contributors

Conventions

INTRODUCTION

Deployment Trend Towards Converged Infrastructure (CI)

Design Trend Towards Software-Defined Data Centers (SDDCs)

Hyper-Converged Infrastructure

DELL EMC CONVERGED-INFRASTRUCTURE PLATFORMS OVERVIEW

Block Architecture

Rack Architecture

Appliance Architecture

VxRail Product Profile

VXRAIL HARDWARE ARCHITECTURE

VxRail Appliance Cluster

VxRail Networking

VxRail Models and Specifications

VXRAIL SOFTWARE ARCHITECTURE

Appliance Management

VMware vSphere

vSAN

SUPPORT FOR EXTERNAL NETWORK STORAGE

ISCSI with VxRail

NFS with VxRail

INTEGRATED SOLUTIONS

VMware Horizon

Native Hybrid Cloud (NHC) with Pivotal Cloud Foundry

VxRail VM Replication

Storage Tiering and File Support with CloudArray

Integrated Backup and Recovery with vSphere Data Protection (VDP)

VXRAIL SERIES USE CASES

Use Case: Platform as a Service (PaaS)

Use Case: Hybrid Cloud

Use Case: Analytics and Collaboration

Use Case: Server Workloads

Use Case: End User Computing Services (EUC)

Use Case: Simplifying the Distributed Enterprise Environment

PRODUCT INFORMATION

Product Support

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