Microsoft Windows Server 2012 thin provisioning space

Microsoft Windows Server 2012
thin provisioning space reclamation using
the IBM XIV Storage System
Author: Eric B. Johnson
Editors: Ted Gregg
Date: February 2013
Version: 1.0
Table of Contents
Executive summary ....................................................................................................................................... 3
Target audience ............................................................................................................................................ 3
Symantec Storage Foundation user considerations ..................................................................................... 4
VMware virtualization environment guidance ............................................................................................. 4
Space reclamation introduction.................................................................................................................... 4
Microsoft and IBM XIV Gen3 SCSI UNMAP support concepts ...................................................................... 5
Microsoft SCSI UNMAP support summary for the IBM XIV Storage System Gen3................................... 7
IBM XIV Storage System Gen3 ...................................................................................................................... 8
Introducing IBM XIV Storage System Gen3 Model 214 .......................................................................... 10
Microsoft thin provisioning and storage space reclamation features ........................................................ 11
Thin provisioning LUN identification....................................................................................................... 11
Threshold notification ............................................................................................................................. 12
Space reclamation using SCSI UNMAP .................................................................................................... 14
Storage device logical block mapping states .......................................................................................... 15
Microsoft Windows 2012 Data Deduplication ............................................................................................ 15
Microsoft Windows 2012 Data Deduplication support summary .......................................................... 16
Windows Server 2012 Data Deduplication installation steps ................................................................. 17
Triggering immediate Windows 2012 Data Deduplication for a NTFS volume ...................................... 24
Conclusion ................................................................................................................................................... 26
Resources .................................................................................................................................................... 27
Trademarks and special notices .................................................................................................................. 28
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Executive summary
With the release of IBM XIV Storage System Gen3 11.2.x microcode, customers can begin to capitalize
on the highly awaited space reclamation benefits associated with Small Computer System Interface
(SCSI) UNMAP support. While the IBM XIV supports SCSI UNMAP commands for both thick and thin
provisioned volumes, only the latter use case is presented in this white paper since SCSI UNMAP
benefits are typically associated with over-provisioned storage. For Microsoft data centers struggling to
mitigate explosive data propagation, SCSI UNMAP is a valuable option to help control storage sprawl.
Furthermore, SCSI UNMAP functionality is native to Windows Server 2012 which also offers new thin
provisioning developments and supplemental operating system (OS) space reclamation features.
This white paper reveals the simplicity in which Information Technology (IT) teams can now take
advantage of substantial data capacity savings using combined IBM XIV and Microsoft improvements
which include the introduction of the Windows Server 2012 Data Deduplication feature. Likewise,
Microsoft cloud administrators should gain practical insight into highly available (HA) Hyper-V capacity
savings tactics.
Target audience
This documentation is intended for solutions architects, system, and storage administrators that
routinely manage IBM XIV Storage System Gen3 thin provisioned environments. Microsoft Windows
Server 2012 early adapters looking to maximize storage efficiency using the IBM XIV Gen3 should benefit
most from new multi-level space reclamation enhancements. Moreover, these latest thin provision
enhancements should appeal to large to midsize businesses evaluating or seeking additional storage
capacity savings strategies for both physical and virtual machines.
General experience or understanding of the required solution components including Microsoft Windows
Server administration, Microsoft Failover Clustering, Hyper-V virtualization technology, thin
provisioning, data deduplication and XIV Storage System Gen3 administration is recommended.
However, there are technical reviews as well as supplemental references in the remaining sections
below.
Prior to sharing information about new Microsoft space reclamation enhancements now available to the
IBM XIV Storage System Gen3, the following couple of sections direct Symantec Storage Foundation and
VMware users to solution-specific resources.
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Symantec Storage Foundation user considerations
Symantec Storage Foundation provides middleware functionality for its software-based dynamic disks
which is beyond typical Windows NTFS volume definitions. This differentiation carries over to its
alternate space reclamation approach. Rather than using SCSI UNMAP commands, Symantec Storage
Foundation employs SCSI WRITE SAME commands to achieve the same end result. However, SCSI WRITE
SAME space reclamation methods are outside of the scope of this paper. Thus, Symantec Storage
Foundation users can visit the following website for further details regarding space reclamation using
various IBM storage family products including the XIV Storage System:
http://public.dhe.ibm.com/common/ssi/ecm/en/tsw03164usen/TSW03164USEN.PDF
VMware virtualization environment guidance
Unlike Symantec Storage Foundation, VMware vSphere supports SCSI UNMAP commands for its
datastore space reclamation. VMware began supporting SCSI UNMAP commands when it introduced the
VMware vSphere 5.0 storage APIs for Array Integration (VAAI) primitives. However, VMware discovered
issues which affected their Storage vMotion and VM Snapshot consolidation that led them to alter their
SCSI UNMAP support for its newest release – vSphere 5.1. Specifically, vSphere 5.1 does not provide
proactive or automatic space reclamation for SCSI UNMAP commands. Manual user intervention or
scripts must be implemented to realize the SCSI UNMAP benefits preferably outside of peak business
hours. For VMware virtualization environment guidance, review the following IBM Redpaper:
http://www.redbooks.ibm.com
Space reclamation introduction
The demand for IT administrative productivity continues to increase simultaneously as hardware and
resource budgets decrease. This forces many organizations to re-evaluate their data center designs in
the midst of irrepressible data growth trends. With business critical data proliferation frequently
challenging storage-based teams, many IT administrators direct their attention towards maximizing
storage return on investments (ROI) and reducing costs. Hence, customers place much greater demand
on storage vendors for product portfolios with greater efficiency, advanced features and attractive,
competitive pricing. Historically to address storage efficiency, a natural progression ensued which
introduced thin provisioning.
Thin provisioning allows administrators to allocate logical capacity that is greater than a storage
system’s total physical capacity. It does so by using on-demand block allocation of data based on host
writes versus allocating all of the blocks during the initial volume creation. As a result of this on-demand
approach to allocating actual physical storage capacity, customers can realize significant economic
benefits by over-provisioning or thin provisioning their storage. By and large, this is due to not having to
commit considerable storage capacity up front (as with thick provisioning) to users or business groups
that often consume only a fraction of the allocated physical capacity. Consequently, cascading cost
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reductions are observed by diminished storage capacity requirements that contribute to smaller data
center footprints with lower administrative overhead and power and cooling expenses. Even with these
welcomed benefits, for many, thin provisioning lacked distinctive maturity due to space reclamation
deficiencies. More or less, many desired storage array dead space reclamation without having to use
limited or primitive utilities.
In order to fully appreciate dead space reclamation, one must examine the host front-end and the
storage back-end. Once a host writes to a thin provisioned volume, physical capacity is allocated to the
host file system. Unfortunately, if the host deletes the file, only the host file system frees up that space.
The physical capacity of the storage system remains unchanged. In other words, the storage system
does not free up the capacity from the deleted host file which is commonly referred to as “dead space”.
Obviously, this is not the most effective method for handling back-end block-level storage. Ideally, when
a host deletes files, that space is not only reclaimed by the host file system but also the back-end
storage system.
To address this thin provisioning limitation, the T10 Technical Committee established the T10 SCSI Block
Command 3 (SBC3) specification which defines the “UNMAP” command for a diverse spectrum of
storage devices including hard disk drives (HDDs) and numerous other storage media. Using SCSI
UNMAP, IT administrators can now reclaim host file system space and back-end storage dead space
typically within 30 seconds of a host file deletion. However, not only does SCSI UNMAP require T10 SBC3
compliant SCSI hardware, it also requires necessary software application programming interfaces (APIs)
such as those now included in Windows Server 2012 or Windows 8. That being said, previous Windows
OS releases do not support the necessary APIs.
Microsoft and IBM XIV Gen3 SCSI UNMAP support concepts
In order to avoid common misconceptions about Microsoft Windows storage space reclamation using
the T10 SBC3 specification, key additional information is shared. As previously albeit partially disclosed,
Microsoft space reclamation requires APIs which are now included in Windows 8 and Windows 2012
that allow native or 3rd party applications to send TRIM or SCSI UNMAP hints to compliant storage
media. Notably for the IBM XIV Storage System Gen3, storage media refers to SCSI HDDs.
From an OS perspective, Microsoft Windows uses file TRIM or FILE_LEVEL_TRIM code to trigger storage
space reclamation using either TRIM or SCSI UNMAP requests depending on the target device types.
Consequently for Microsoft Windows solutions, file TRIM and space reclamation are often used
interchangeably due to their obvious relationship. However, this can be confusing since TRIM used in
this context is completely different than T13 Advanced Technology Attachment (ATA) device standards
which define ATA-specific TRIM commands. To help clarify, only SCSI devices can interpret T10 SBC3
UNMAP commands and only ATA devices, better known as Integrated Drive Electronics (IDE) devices,
can interpret T13 TRIM commands. That said, Windows determines the storage media type when the
device, or XIV LUN for the practical purposes of this paper, is attached or mapped to the host.
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During the device enumeration process, Windows detects the device identity and if it is SCSI UNMAP or
ATA TRIM capable. When a large OS file deletion occurs, Windows triggers a FILE_LEVEL_TRIM and
converts the deletion or FILE_LEVEL_TRIM notification into an equivalent UNMAP request to pass to the
storage device. Acting as interpreter, the storage port driver stack translates the UNMAP request into a
SCSI UNMAP command or ATA TRIM command according to the detected storage device type. For all
intents and purposes of this document, IBM XIV Storage System Gen3 administrators should only be
concerned with SCSI UNMAP but it helps to be aware of ATA TRIM concepts for other applicable
solutions.
For Microsoft Windows physical environments, SCSI UNMAP behavior is fairly straightforward both at
the operating system and XIV storage level. Within Microsoft Windows, when a file is written to an NTFS
volume, the XIVGUI or XCLI interface immediately reflects an increase in the XIV volume used capacity
for the consumed space. When a file is permanently deleted on that NTFS volume, the XIVGUI or XCLI
used capacity for the XIV volume usually decreases within 30 seconds. It’s a valuable new real-time
space reclamation advancement that’s simple to comprehend and almost instantaneous. Even though
SCSI UNMAP behavior for Microsoft virtual machines is slightly more complex, it is also greatly
welcomed since Hyper-V clouds continue to multiply throughout global data centers.
For Microsoft Hyper-V virtual cloud environments, SCSI UNMAP behavior is more complex since space
reclamation can occur at multiple levels and often involves failover clusters. For Hyper-V host-based file
deletions that involve VM files or virtual machine storage migrations to other local or remote
destinations, space reclamation is identical to the aforementioned physical machine description. If the
Hyper-V host file (i.e. VHD, VHDX, ISO, etc.) is permanently removed from the host NTFS volume, the
host file system and XIV volume used capacity decreases and free space increases.
For Hyper-V VM guest-based file deletions, space reclamation occurs at 3 different levels:

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Guest OS NTFS volume frees up space
XIV volume used capacity decreases
Host VHDX file size decreases
The first two processes are dynamic and near-instantaneous while the latter requires manual user
intervention.
Manual user intervention is mandatory since Hyper-V host VHDX files are mostly read-write files locked
by the VM guest OS which require the file to be unlocked in order to shrink in size. Therefore host VHDX
files do not currently allow real-time space reclamation. To be more precise, the guest-based file
deletions will not trigger a decrease in the host VHDX file size until additional administrative actions
occur. So when a Hyper-V VM user deletes files, only the guest NTFS volume and XIV volume reclaim
space at that time.
To trigger Hyper-V host space reclamation for the VHDX file, the VM must be offline. Hyper-V cloud
administrators can perform the following to decrease the host VHDX file size:
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1. Within the VM guest OS, launch the Windows PowerShell with administrator privileges.
2. Run this command:
‘Optimize-Volume -DriveLetter F -ReTrim –Verbose’ (substitute appropriate drive letter)
Note: If space reclamation results do not occur in a timely or predicted fashion, always initiate
host or guest OS volume optimizations such as above. Quite often this course of action
accelerates the desired space reclamation.
3. Shutdown or restart the VM guest OS.
4. Upon shutdown of the VM guest OS, administrators observe an immediate decrease in the host
file size of the VM VHDX file(s).
Note: Since these steps require production VMs to be offline, cloud administrators should
synchronize host VHDX space reclamation with other guest OS maintenance windows that
require downtime. Combining these tasks should help minimize production VM outages.
Even though Hyper-V space reclamation is more involved, the rewards far outweigh the slight virtual
complexities. This also applies to Microsoft Hyper-V failover clusters. HA SCSI UNMAP behavior is not
hindered or negatively impacted by failover cluster resources. Subsequently, space reclamation is fully
supported for Hyper-V HA VMs that reside on cluster disks or cluster shared volumes (CSVs). VM quick
and live migrations are also supported and do not affect space reclamation functionality for Hyper-V
cluster hosts or their corresponding guests. Additionally, SCSI UNMAP is supported for HA Hyper-V VM
IDE and SCSI controller hard disks consisting of fixed and dynamically expanding VHDX files, passthrough disks, fibre channel adapter (FCA) N-Port ID Virtualization (NPIV) disks and differencing disks.
Important: No matter the additional hypervisor or cluster stack layers, it is the detected storage media
that determines how Windows passes FILE_LEVEL_TRIM to the target device (using SCSI UNMAP for XIV
HDDs). For example, Hyper-V VM default system volumes that reside on an XIV volume and use virtual
IDE controllers, still benefit from SCSI UNMAP.
Microsoft SCSI UNMAP support summary for the IBM XIV Storage System Gen3

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Requires IBM XIV Storage System Gen3 code level 11.2.x or greater
IBM XIV Gen3 FC and iSCSI volumes
Note: The smallest atomic unit that can be reclaimed via SCSI UNMAP is 1MB which corresponds
to the fundamental building block size of an XIV volume known as a partition.
Note: Although XIV volume used capacity reflects space reclamation upon host deletions, actual
pool capacity is reclaimed in 17 GB units, also known as slices. XIV pool space reclamation occurs
once an entire 17 GB slice is freed. This is due to the XIV grid architecture which always defines
logical volume physical capacity in multiples of 17 GB (decimal) since each volume spans all
physical drives in the system.
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
IBM XIV Gen3 mirror volumes
Note: SCSI UNMAP is supported for volumes that use synchronous mirroring as long as all XIV
Storage Systems are using 11.2 code. SCSI UNMAP is not supported for volumes that use
asynchronous mirroring.

IBM XIV Gen3 volumes that contain snapshots
Note: Depending on XIV thin provisioning threshold values, volume file deletions may trigger
snapshot deletions due to space exhaustion. Snapshot deletion priorities can be defined during
the initial snapshot creation and extra precautions should be taken not to exhaust XIV hard or
physical capacity.
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IBM XIV Gen3 snapshot volumes
Microsoft Windows Server 2012
Windows 8
Microsoft failover cluster
o Cluster shared volume (CSV)
o Cluster disk
Hyper-V
o VHDX
o PassThru disks
o Virtual SCSI Controller or Virtual Fibre Channel Adapter disks
IBM XIV Storage System Gen3
Even without the latest space reclamation benefits, the IBM XIV Storage System Gen3 consistently
exceeds customer expectations by continuing to evolve and offer enhanced efficiency, more advanced
features and attractive, competitive pricing to an ever-increasing number of businesses. Building upon
this tradition, IBM introduced a new XIV Gen3 model as well as microcode 11.2, which satisfies T10 SCSI
UNMAP compliance and produces highly anticipated space reclamation advantages. All of which
strengthens an existing and immensely popular enterprise-class feature set for a storage system that
departs from the unnecessary complexities linked to conventional redundant array of independent disks
(RAID) solutions.
Upon examining the IBM XIV Storage System Gen3 closer, there are no traditional RAID requirements for
assigning specific spindles (disks) to individual storage pools. Both XIV regular (thick) and thin
provisioned pools are essentially managed the same and there are no major physical distinctions
between the pool types. Pool types are mainly distinguished by minor metadata differences.
Accordingly, pools and their constituent volumes are created instantaneously since only XIV metadata
tables are modified. Due to this inherent architectural design, the IBM XIV provides unorthodox thin-like
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provisioning for all of its virtual storage. Actual thin provisioned pools are primarily differentiated by
their ability to over-provision logical capacity that is greater than the pool’s physical capacity.
Consequently and as noted previously, the latest SCSI UNMAP space reclamation benefits apply to both
regular (thick) and thin provisioned pools which form one of many important elements in the IBM XIV
Gen3’s unique storage design.
Contained within the IBM XIV Gen3 pools are volume partitions which provide the foundation of its
unique virtual storage design. XIV partitions are the fundamental building blocks used to create XIV pool
volumes and consist of primary and secondary mirrored data copies mapped to separate disks. Using
sophisticated data distribution algorithms which preserve data redundancy and performance
equilibrium, XIV partitions are automatically and dynamically distributed across all disks. Since the
distribution algorithms pseudo-randomly distribute the data across all of the spindles, there is no LUN
locality of reference to a particular disk or subset of disks, ensuring no hot-spots regardless of workload
changes over time. As a result, the IBM XIV Storage System self-tunes in response to application I/O
patterns as well as configuration and capacity changes commonly associated with physical and virtual
environments all while providing some of the storage industry’s best data protection properties.
XIV data protection employs active/active N+1 redundancy of all data modules, disks, interconnect
switches, and uninterruptible power supply (UPS) units. The XIV also contains multipath FC and iSCSI
host connections for each interface module. Three built-in UPS units protect all disks, cache and
electronics with redundant power supplies and fans, which further promote hardware and software
business critical availability and reliability. The XIV uses predetermined data distribution algorithms
which help ensure fast recovery from major and minor faults using pre-failure detection and proactive
corrective healing. In the event of module or disk failures, global spares striped across all disks quickly
redistribute data back to a fully redundant state. During such events, the performance impact is notably
minimized.
This minimal performance impact is due to the IBM XIV Storage System Gen3 extremely competitive
performance characteristics which readily meet demanding physical or virtual workloads. The XIV highly
scalable, distributed architecture provides a combined total of up to 360 GB of cache and individual
modules powered by quad-core Intel Xeon processors. Up to six dedicated host interface modules
ensure optimal, balanced data distribution among all 180 2TB or 3TB disks to help eliminate hot spots.
This data distribution feature is quite significant due to the popularity of using larger LUNs for multiple
VMs typically deployed in cloud environments. In addition to data integrity benefits, since every LUN is
striped across all 180 disks, the chance of saturating storage IO is greatly reduced when compared to
conventional architectural approaches using RAID sets and hot spares.
As conveyed thus far, the IBM XIV Gen3 unique and sophisticated storage design is very user-friendly
and provides extremely low administrative overhead. To no surprise, the actual management utilities
are categorically intuitive and extremely easy to use. So much so, that IBM continues to develop almost
identical graphical user interfaces for other members of its storage portfolio in response to customer
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popularity. This unique evolutionary architecture coupled with truly uncomplicated management
software is vastly improved with the XIV Storage System Gen3 family and helps provide the following
key benefits:

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Up to 4 times the throughput (10 GB/sec) of the previous XIV generation, improving
performance for business intelligence, archiving and other I/O-intensive applications
Up to 3 times improved response time of the previous XIV generation, enabling faster
transaction processing and greater scalability for online transaction processing, database and
email applications
Industry-leading rebuild times in the event of disk or module failures (less than 60 minutes for 2
TB drives)
Innovative snapshot functionality that includes snap-of-snap, restore-of-snap and a nearly
unlimited number of snapshots
Non-disruptive maintenance and upgrades
Per host/cluster QoS capability to prioritize workloads based on business criticality
Power to serve even more applications from a single system with a substantial hardware
upgrade that includes an InfiniBand interconnect, larger cache (up to 360 GB of combined
memory), faster SAS disk controllers and increased processing power—plus, each Gen3 interface
module delivers 8 Gb FC and 1 Gb iSCSI connectivity
Boost highly random application workloads up to 4.5X with optional SSD Cache
With the XIV family’s “all-inclusive” pricing model, there are no hidden costs for multipath
software or replication features — specifically, every XIV includes the following with purchase:
snapshot capability, thin provisioning, asynchronous and synchronous data replication,
advanced management, performance reporting, monitoring and alerting, and full support of
Microsoft technologies including GeoClustering, Volume Shadow Copy Services (VSS) and MPIO
Introducing IBM XIV Storage System Gen3 Model 214
In order to maintain product leadership and increase customer satisfaction, host performance, and
support the IBM smarter planet program with energy star compliance, IBM welcomes its latest XIV
family member – the IBM XIV Storage System Gen3 Model 214. Building upon an existing strong
foundation, the newest XIV Gen3 model provides the following improvements:


New cloud and virtualization enhancements
o 10 GbE iSCSI host connectivity
o Microsoft Windows Server 2012 support for latest features such as Hyper-V, VSS, and
failover clustering
Improved storage system self-optimization and performance
o Reduce disk rebuilds by 60% - during heavy workloads, fully utilized 2 TB drives can be
rebuilt in 26 minutes
o Faster sequential read performance up to 13.7 GB/s, enabling high service level
agreements for VM cloning, multimedia, and backup workloads
o Up to 15 six-core Intel Xeon processors providing 90 physical cores or 180 logical cores
using Hyper-Threading technology
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
Decreased TCO through greater energy efficiency and capacity optimization
o Promotes green data center strategies by lowering carbon footprints and aggregate
power consumption by up to 16% with new power supply units
o SCSI UNMAP space reclamation for both physical and virtual hosts
Microsoft thin provisioning and storage space reclamation features
Supported by both IBM XIV Gen3 Storage System models, Microsoft storage reclamation is built into its
Windows thin provisioning features, not to be confused with OS features or roles. A Windows Thin
Provisioning feature literally does not exist. Instead, the Windows thin provisioning feature refers to an
OS framework that yields supplemental thin provisioning functionality. Since Microsoft Windows 8 and
Windows 2012 both adopted the T10 SCSI Block Command 3 (SBC3) standard specification which now
provides the necessary OS thin provisioning framework, storage vendors can use the same standard to
augment customer storage monitoring and utilization without requiring additional or proprietary
applications.
In order to ensure storage vendor T10 SBC3 compliance, Microsoft also introduced new Windows Server
2012 Thin Provisioning Logo certification tests. Storage product participation involves passing numerous
thin provision functionality and performance tests which include storage space reclamation. Once the
passing test results are submitted to and reviewed by Microsoft, storage products become Windows
Thin Provisioning certified. The IBM XIV Storage System Gen3 with 11.2.x code is currently undergoing
Windows Thin Provisioning certification testing. However, the IBM XIV Gen3 has implemented the T10
SBC3 standard and thus unlocks new Windows thin provisioning benefits even though the official
Microsoft certification is still pending.
Microsoft Windows 8 and 2012 coupled with the T10 SBC3-compliant IBM XIV Storage System Gen3
(code level 11.2.x) now provide:
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Thin provisioning LUN identification
Threshold notification as well as permanent resource exhaustion handles
Storage space reclamation using SCSI UNMAP storage hints
Storage device logical block mapping states
Thin provisioning LUN identification
In the past, only storage administrators could tell whether a volume was thick or thin provisioned. With
the latest Windows 2012 thin provisioning framework enhancements, all Windows users can determine
the LUN identification. To verify the new thin provisioning LUN identification, launch the Windows
Defragment and Optimize Drives utility located in the Administrative Tools. Under the Media type
column of the Optimize Drives window, notice IBM XIV Gen3 thin volumes show up as ‘Thin provisioned
drives’ as depicted in the screenshot below.
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Threshold notification
Pool and volume threshold alerts which were formerly detectable using IBM XIV storage management
tools are now also available in Windows Server 2012 too. When a threshold is exceeded on the IBM XIV
Storage System Gen3, the alerts are triggered as Windows System Event logs using Windows temporary
or permanent resource exhaustion handles which allow the SAN storage to directly update the OS.
Fortunately, there is no need to configure anything for the IBM XIV Gen3 to immediately profit from the
new Windows Server 2012 resource exhaustion handles. The XIV only supports and enables permanent
resource exhaustion by default. For Windows System Event Log threshold notification, storage
administrators can define pool alert threshold values using the XIVGUI as depicted below.
XIVGUI > Systems > System Settings > Pool Alerts Thresholds
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Once the XIV pool alert thresholds are exceeded, there are two types of events that are triggered. At the
storage level, the XIVGUI reports the pool alerts at the bottom left of the system view as well as the
monitor alerts view.
Note: At the bottom left of the XIVGUI, mouseover the red alert warning icon to view additional details.
XIVGUI > View > Monitor > Alerts
Note: For testing purposes, the XIVGUI alerts above were triggered with pool threshold values lower
than the default values.
At the OS level, the Windows System Event log will report the following system events:
Event ID
144
145
146
147
148
149
General Information
Threshold notification without additional information
Threshold notification without specific information
Threshold notification with used LUN capacity and available LUN capacity information
Threshold notification with used LUN capacity and available pool capacity information
Threshold notification with used pool capacity and available LUN capacity information
Threshold notification with used pool capacity and available pool capacity information
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Example System Event Log ID 144 for XIV thin provisioned volume threshold trigger:
Log Name: System
Source:
disk
Date:
1/10/2013 10:22:29 PM
Event ID: 144
Task Category: None
Level:
Warning
Keywords: Classic
User:
N/A
Computer: isvx8.xiv.tucson.ibm.com
Description:
Disk 13 has crossed a capacity utilization threshold.
If a permanent resource exhaustion threshold is reached, the following also occurs:


A Windows System Event log ID 150 is generated
The thin-provisioned XIV volume is taken offline and becomes unavailable until the storage
administrator increases the volume capacity and/or pool capacity
Space reclamation using SCSI UNMAP
By default, Windows 8 and 2012 enable real-time space reclamation using SCSI UNMAP. As previously
described, anytime a large file is deleted, multi-level space reclamation occurs. However, this may
impact performance depending on how often users or applications delete large files. Proper planning
should help to alleviate any real-time space reclamation performance impacts and can be accomplished
establishing performance baselines.
If Windows space reclamation planning identifies a high probability of performance impact, consider the
following option:

Real-time space reclamation can be disabled for large file deletions in the Windows registry.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem
Set the DisableDeleteNotification value to 1
Note: This Windows registry setting affects all LUNs. For further information, visit the following
website:
Plan and Deploy Thin Provisioning
http://technet.microsoft.com/en-us/library/jj674351.aspx
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Storage device logical block mapping states
Windows Server 2012 now has the ability to detect the storage device logical block mapping states of
thin provisioned LUNs. For storage management operations, Windows contains a new API
implementation known as an IOCTL DSM allocation which retrieves the logical block address (LBA) status
of thin provisioned LUNs. All logical blocks are grouped into slabs or clusters which are classified into
mapped, de-allocated or anchored states which Windows considers unmapped states. This is
transparent to users and ensures the Windows thin provisioning framework, which includes space
reclamation, performs as intended.
For further information about the Windows 2012 Thin Provisioning features, reference the following
website:
http://msdn.microsoft.com/en-us/library/windows/hardware/hh770514.aspx
Microsoft Windows 2012 Data Deduplication
In addition to the space reclamation benefits associated with SCSI UNMAP, Microsoft Windows Server
2012 introduced a new Data Deduplication feature that operates at the storage block level. Windows
Data Deduplication is very compelling and highly effective for reducing file server, user profile, Hyper-V
library, and other widespread data capacity requirements. The Windows Data Deduplication feature also
provides compounded space reclamation benefits. After Data Deduplication is configured and enabled
for a volume, not only does the file system reclaim space but Windows Data Deduplication also triggers
SCSI UNMAP to reclaim the SAN storage free space. However, unlike the default space reclamation
behavior during Windows Server 2012 file deletions, data deduplication does not take place in real-time.
It can be easily automated through scheduling as well as manually triggered but falls into the postprocessing category.
Even though Windows Data Deduplication is designed for low memory and CPU use and the default
deduplication policy settings are usually sufficient to achieve excellent savings without impacting normal
server workloads, it is post-processed to help eliminate potential performance impacts. Basically, a
server needs one CPU core and 350 MB of free memory to run a deduplication job per volume which
scales with additional CPU core processors and available memory. CPU and memory resources are used
for a sub-file chunking algorithm which enables Data Deduplication to find and remove duplicate data by
breaking files into variable sizes, typically 32-128 KB, all without compromising file integrity or fidelity.
The file segments form chunk boundaries which are defined by a Rabin fingerprint-based sliding window
hash and eventually compressed and placed into stores. These chunk stores are hidden in the volume
root System Volume Information (SVI) folder. In the end, the files are replaced by reparse points which
map the data streams and chunks in order to reconstitute the files if later required.
In general, NTFS volumes that contain infrequently modified files are the best candidates for Windows
Data Deduplication. Additionally, customers may elect to automate or run deduplication jobs after peak
business production hours to ensure maximum performance and optimization. For in-depth information
about Windows 2012 Data Deduplication, reference the following website:
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Data Deduplication Overview
http://technet.microsoft.com/en-us/library/hh831602.aspx
Microsoft Windows 2012 Data Deduplication support summary
Windows 2012 Data deduplication supports:



Windows Server operating systems beginning with Windows Server 2012
NTFS data volumes including regular cluster disk resources
SQL Server and Exchange Server backup volumes
Windows 2012 Data Deduplication does not support:







System or boot volumes
Remote mapped or remote mounted drives
Cluster shared volumes (CSV)
Live VM files
Active SQL Server databases
Files that are open and constantly changing or have high I/O requirements
Setting hard quotas on volume root folders that have deduplication enabled
Note: Microsoft suggests not using Windows Data Deduplication for Hyper-V hosts, VDI VHDs, WSUS,
SQL Server or Exchange Server, and large files that are 1 TB or greater in size.
Windows omits the following from data deduplication:





Encrypted files
Windows system state data files
Files smaller than 32 KB
Non data deduplication reparse points
Files with metadata extended attributes
Note: User-defined folders and file extensions can also be excluded when configuring volume data
deduplication.
During the planning stages, consider using the Data Deduplication Savings Evaluation Tool to help
determine which server solutions benefit most. This Windows 2012 native utility is extracted to
%systemroot%\system32 once the Data Deduplication feature is installed as described in the next
section. For further information about the Data Deduplication Savings Evaluation Tool, reference the
following website:
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Evaluate savings with the Deduplication Evaluation Tool (DDPEVAL.exe)
http://blogs.technet.com/b/klince/archive/2012/08/09/evaluate-savings-with-the-deduplicationevaluation-tool-ddpeval-exe.aspx
To launch the utility from the command line, run the following:
C:\Windows\System32>ddpeval /?
Data Deduplication Savings Evaluation Tool
Copyright (c) 2012 Microsoft Corporation. All Rights Reserved.
Usage:
ddpeval <path> [/V] [/E] [/O:<filepath/name>]
<path> Drive, directory or share to be evaluated.
/V Verbose.
/E Process files with extended attributes.
/O Output to file.
<filepath/name> Output file name.
/? Help.
C:\Windows\System32>ddpeval f:\ /V /O:c:\ddpeval_f_test1.txt
Data Deduplication Savings Evaluation Tool
Copyright (c) 2012 Microsoft Corporation. All Rights Reserved.
Progress: 95%
C:\Windows\System32>ddpeval f:\ /V /O:c:\ddpeval_f_test1.txt
Data Deduplication Savings Evaluation Tool
Copyright (c) 2012 Microsoft Corporation. All Rights Reserved.
Evaluated folder: f:\
Evaluated folder size: 647.96 GB
Files in evaluated folder: 16438
Processed files: 8638
Processed files size: 647.91 GB
Optimized files size: 335.88 GB
Space savings: 312.03 GB
Space savings percent: 48
Optimized files size (no compression): 366.41 GB
Space savings (no compression): 281.50 GB
Space savings percent (no compression): 43
Note: Test durations for the Data Deduplication Savings Evaluation Tool vary based on volume
size, file quantities, file types, file or folder exclusions, file sizes, and server resource availability.
Windows Server 2012 Data Deduplication installation steps
Perform the following steps to install and test the new Windows Server 2012 Data Deduplication
feature:
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1. In the left pane of the Server Manager, highlight Local Server, expand the top right menu bar.
Under Manage, select Add Roles and Features.
2. In the Before you begin section of the Add Roles and Features Wizard, click Next.
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3. In the Select installation type of the Add Roles and Features Wizard, select Role-based or
feature-based installation and click Next.
4. In the Select destination server section of the Add Roles and Features Wizard, choose Select a
server from the server pool. Make sure to select the desired server for adding the new feature
and click Next.
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5. In the Select server roles section of the Add Roles and Feature Wizard, expand File and Storage
Services. Expand File and iSCSI Services and select Data Deduplication.
6. Upon selecting Data Deduplication above, the following feature dependency popup appears.
Click Add Features.
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7. Review the Server Role selection and click Next.
8. In the Features section of the Add Roles and Features Wizard, simply click Next.
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9. In the Confirmation Installation selections section of the Add Roles and Features Wizard,
review the selected role and its dependencies and click Install.
10. In the Results section of the Add Roles and Features Wizard, confirm the successful installation
and click Close.
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11. In the left pane of the Server Manager, highlight File and Storage Services and click on
Volumes. Right click the desired volume and select Configure Data Deduplication.
12. In the Deduplication Settings dialog box, select “Enable data deduplication” and add other
desired parameters.
Note: If testing deduplication, place a value of 0 days in the “Deduplicate files older than…” field
as highlighted above.
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13. Once deduplication is enabled on the volume, take note of the “Deduplication Rate” and
“Deduplication Savings” values. The Deduplication values start at 0% until the deduplication job
is executed as scheduled or immediately using the appropriate PowerShell commands.
Triggering immediate Windows 2012 Data Deduplication for a NTFS volume
Once Windows 2012 Data Deduplication is enabled, perform the following steps to manually trigger the
capacity savings outside of default or user-defined schedules:
Note: Prior to forcing deduplication to run on a volume, record the volume used capacity in the XCLI or
XIVGUI. Capturing the before and after values provides the exact space reclamation savings. Of course,
the deduplication durations will vary as previously noted.
From the XCLI:
Before:
XIV 7820045>>vol_list
Name Size (GB) Master Name Consistency Group Pool
Creator Used Capacity (GB)
hyper_v_library_vol_01 2219
xiv_UNMAP_test_thin_pool_01 admin
695
After:
XIV 7820045>>vol_list
Name Size (GB) Master Name Consistency Group Pool
Creator Used Capacity (GB)
hyper_v_library_vol_01 2219
xiv_UNMAP_test_thin_pool_01 admin
368
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Note: By running the XCLI vol_list command multiple times, the storage administrator can periodically
check the Windows Deduplication and SCSI UNMAP progress. The XCLI volume "Used Capacity (GB)"
should decrease in value as seen above.
From the Windows PowerShell (PS) using administrator privileges:
PS C:\Users\administrator.XIV> Start-DedupJob L: -type Optimization
Type
ScheduleType
StartTime
Progress State
---------------------------------Optimization
Manual
0%
Queued
Volume
-----L:
PS C:\Users\administrator.XIV> Get-DedupJob
Type
ScheduleType
StartTime
Progress State
---------------------------------Optimization
Manual
3:23 PM
61 %
Running
Volume
-----L:
PS C:\Users\administrator.XIV> Get-DedupJob
Type
ScheduleType
StartTime
Progress State
---------------------------------Optimization
Manual
3:23 PM
96 %
Running
Volume
-----L:
Note: The data deduplication process can also be checked using the following command. Just like the
other XCLI and Windows PS examples, it can be run multiple times to view the progress. The
"SavedSpace" and "SavingsRate" values should increase over time.
From the Windows PowerShell (PS) using administrator privileges:
PS C:\Users\administrator.XIV> Get-DedupVolume L:
Enabled
SavedSpace
SavingsRate
Volume
------------------------------True
245.48 GB
38 %
L:
PS C:\Users\administrator.XIV> Get-DedupVolume L:
Enabled
SavedSpace
SavingsRate
Volume
------------------------------True
288.75 GB
45 %
L:
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Conclusion
The IBM XIV Storage System Gen3, including the latest model and 11.2 microcode, now offers enhanced
efficiency and more advanced features which allow customers to tap into the latest Microsoft Windows
Server 2012 thin provisioning benefits. These new Windows framework benefits include thin
provisioning LUN identification, threshold notification, SCSI UNMAP space reclamation, and storage
device logical block mapping states. Thin provisioning dead space deficiencies are no longer a concern
and IT administrators can manage data capacity demands and control storage sprawl much better.
Moreover, Microsoft cloud administrators realize multi-level physical and virtual space reclamation
benefits which help mitigate Hyper-V data capacity concerns. Finally, these storage optimization and
efficiency advances combined with Microsoft Windows Server 2012 Data Deduplication allow IT
administrators to maximize storage ROI all while helping to reduce costs.
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Resources
The following websites provide useful references to supplement the information contained in this
paper:
IBM XIV Storage System series
http://www-03.ibm.com/systems/storage/disk/xiv/index.html
T10 SBC3 Specification
http://www.t10.org/cgi-bin/ac.pl?t=f&f=sbc3r27.pdf
New API allows apps to send "TRIM and Unmap" hints to storage media (Windows)
http://msdn.microsoft.com/en-us/library/windows/desktop/hh848053%28v=vs.85%29.aspx
Thin Provisioning in Windows Server 2012
http://msdn.microsoft.com/en-us/library/windows/hardware/hh770514.aspx
Introduction to Data Deduplication in Windows Server 2012
http://blogs.technet.com/b/filecab/archive/2012/05/21/introduction-to-data-deduplication-inwindows-server-2012.aspx
About Data Deduplication (Windows)
http://msdn.microsoft.com/en-us/library/windows/desktop/hh769303%28v=vs.85%29.aspx
Evaluate savings with the Deduplication Evaluation Tool (DDPEVAL.exe)
http://blogs.technet.com/b/klince/archive/2012/08/09/evaluate-savings-with-the-deduplicationevaluation-tool-ddpeval-exe.aspx
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Trademarks and special notices
© Copyright IBM Corporation 2012.
References in this document to IBM products or services do not imply that IBM intends to make them
available in every country.
IBM, the IBM logo, and ibm.com are trademarks or registered trademarks of International Business
Machines Corporation in the United States, other countries, or both. If these and other IBM trademarked
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current list of IBM trademarks is available on the Web at "Copyright and trademark information" at
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Java and all Java-based trademarks and logos are trademarks or registered trademarks of Oracle and/or
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Microsoft, Windows, Windows NT, and the Windows logo are trademarks of Microsoft Corporation in the
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Other company, product, or service names may be trademarks or service marks of others.
Information is provided "AS IS" without warranty of any kind.
All customer examples described are presented as illustrations of how those customers have used IBM
products and the results they may have achieved. Actual environmental costs and performance
characteristics may vary by customer.
Information concerning non-IBM products was obtained from a supplier of these products, published
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All statements regarding IBM future direction and intent are subject to change or withdrawal without
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Some information addresses anticipated future capabilities. Such information is not intended as a
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information is presented here to communicate IBM's current investment and development activities as a
good faith effort to help with our customers' future planning.
Performance is based on measurements and projections using standard IBM benchmarks in a controlled
environment. The actual throughput or performance that any user will experience will vary depending
upon considerations such as the amount of multiprogramming in the user's job stream, the I/O
configuration, the storage configuration, and the workload processed. Therefore, no assurance can be
given that an individual user will achieve throughput or performance improvements equivalent to the
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Photographs shown are of engineering prototypes. Changes may be incorporated in production models.
Any references in this information to non-IBM websites are provided for convenience only and do not in
any manner serve as an endorsement of those websites. The materials at those websites are not part of
the materials for this IBM product and use of those websites is at your own risk.
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