four ways to lower the cost of replication

WHITE PAPER
FOUR WAYS TO LOWER
THE COST OF REPLICATION
How an Ultra-Efficient, Virtualized Storage Platform Brings
Disaster Recovery within Reach for Any Organization
I
JANUARY 2010
FOUR WAYS TO LOWER THE COST OF REPLICATION | WHITE PAPER
1
EXECUTIVE OVERVIEW
Within the last decade, replication technologies have come
pool presented to servers. A single command can be used
to play a major role in the data protection paradigm. At first,
to create and provision a logical unit number (LUN) from any
replication processes required large, duplicate systems for off-
part of the pool and map it to a physical host, simplifying data
site recovery, with a price tag that shut out all but the largest of
management and optimizing storage resources. The remote
enterprise customers. But more recent innovations have helped
replication of virtual volumes means that mission-critical data
to dramatically cut cost and complexity, making disaster
is fully protected and quickly recoverable, even in the event of a
recovery (DR) a viable solution for organizations of all sizes.
site-wide disaster.
Today, even small IT groups with limited resources can create
a cost-effective plan for both near-line and off-site replication
Because the Compellent SAN virtualizes storage at the disk
over heterogeneous storage platforms.
level, read/write operations are spread across all the drives in
the storage pool and multiple requests are processed in parallel
Whether you are currently using tape backup and want to create
for optimum performance. Virtual volumes can span multiple
a faster, more reliable data protection framework, or need to
heterogeneous arrays, and administrators can allocate storage
increase efficiencies within your current DR infrastructure,
based on usage, reducing both the likelihood of underutilized
Compellent offers a range of technologies that bring the cost of
drives and the once-common issue of inadequate space.
replication within reach. This white paper outlines four key ways
System administrators can respond immediately to changing
to drive down replication costs while delivering enterprise-class
storage requirements and ease management by adding capacity
performance and manageability with Compellent Fluid Data
to virtual volumes when pre-set thresholds are reached.
storage:
A virtualized storage environment also enables administrators
1. Storage Virtualization – abstracts and aggregates
physical drives into a shared pool of storage, ensuring
data availability and rapid recovery for non-stop business
environments.
to quickly and easily assign and manage virtual volumes from a
2. Thin Replication – utilizes space-efficient, continuous
snapshots to protect data, yielding substantial savings in
storage hardware, bandwidth and management.
ability to employ less IT staff to manage larger amounts of data
3. Portable Volume – dramatically reduces the timeframe for
initial replication synchronization by using pre-configured
external hard drives instead of high-speed data links or
duplicate arrays.
centralized user interface. As needs change, more space can be
provisioned on the fly in a matter of a few mouse clicks without
taking the system offline. Given today’s budget constraints, the
brings welcome increases in return on investment (ROI) and a
parallel reduction in total cost of ownership (TCO ).
In addition, storage virtualization ensures data availability and
recoverability by safeguarding against all possible points of
failure along the SAN. Compellent’s clustered controllers operate
in unison, but connect to drives and enclosures independently,
4. Scalable Serial Attached SCSI (SAS) – allows for the
combination of high-performance and high-capacity drives
in a single enclosure, providing remote site configuration
flexibility and reducing costs while enabling administrators
to leverage enterprise functionality like automated tiering.
providing higher availability than traditional implementations.
1. Increase Availability and Recoverability with
Virtualization
Virtual Ports deliver yet another level of hardware virtualization
Storage virtualization is the backbone of any cost-effective plan
port. This not only enhances the performance of existing I/O
for data protection and business continuity. With Compellent
hardware – increasing port capacity, disk bandwidth and I/O
Fluid Data storage, all the physical disk drives in the system
connectivity – but enhances failover capabilities. Virtual Ports
are abstracted and aggregated into a single virtual storage
also eliminate the need for dedicated reserve hardware ports,
Dual paths from servers to disk drives, along with automatic
controller failover, provide high resilience. And non-disruptive
software upgrades, performed without requiring the shut-down
of applications, ensure continuous data access.
by enabling multiple virtual nodes to share a single physical
FOUR WAYS TO LOWER THE COST OF REPLICATION | WHITE PAPER
2
increasing flexibility and mobility. With support for both FC and
bandwidth requirements and configure replication processes
iSCSI, this increased flexibility reduces replication expenditures
based on actual Replay size using an intuitive interface. Transfer
for both entry-level and enterprise systems, delivering end-to-
rates can be customized based on link speed, time of day and
end virtualization with the greatest possible efficiency.
replication priority. In addition, Replays can be used to test new
applications and service packs without disruption, efficiently
SSD
FC
SAS
SATA
RAID 10
RAID 5
RAID 6
15K
10K
7.2K
support boot-from-SAN operations and virtually eliminate
backup windows on production systems.
Because Thin Replication does not require primary and remote
locations to have identical configurations, users have the flexibility
to choose lower-cost drives for remote sites. To further maximize
efficiencies, Fluid Data storage features a built-in Fibre Channel
(FC)-to-iSCSI converter, enabling users to replicate natively over
IP. While most SANs require expensive FC-to-iSCSI conversion,
Compellent’s native iSCSI interface allows users to leverage
their existing infrastructure for additional savings in hardware
and staff training. Whether using traditional FC or cost-effective
Figure 1: Storage virtualization optimizes storage utilization by
abstracting and aggregating physical disk resources into a single
virtual pool of storage presented to servers simply as capacity.
IP-based transfer links, administrators can replicate data from
high-performance SSD, FC or SAS drives at the primary site to
high-capacity SAS or SATA drives at a remote site.
2. Right-Size Storage Assets with Thin
Replication
Changes Only
The challenge of implementing a full-scale replication solution
can seem daunting. IT managers must evaluate their risk
Frankfurt
London
tolerance and performance requirements, and map them to
available hardware budgets and staffing for long-term planning.
Compellent’s Thin Replication technology, called Remote
Instant Replay, provides enhanced data protection while
minimizing cost, time and effort.
Unlike
conventional
solutions,
New York
Thin
Replication
uses
continuous, space-efficient Replays (snapshots) to protect
Figure 2: Thin Replication captures unlimited, space-efficient
snapshots of incremental changes in enterprise data for robust
site-to-site data protection without the need for full-volume clones.
enterprise data. Once an initial Replay of a virtual volume is
taken, the Compellent SAN only needs to capture incremental
changes in data. This eliminates the need to create full-volume
3. Jumpstart Replication with Portable Volume
clones at the replication target site, minimizing initial hardware
For organizations that do not have a dedicated fiber link or other
investments. The SAN can maintain an unlimited number of
high-speed connection, the initial replication synchronization of
Replays in increments defined by the user, and the Replays can
data between primary and remote sites can present a significant
easily be mapped to any server for near-instant recovery.
time and bandwidth challenge. Depending on the size of the
During ongoing replication, the Compellent SAN intelligently
transfers only the changed blocks of data, rather than entire
volumes, optimizing bandwidth utilization and the use of remote
site resources. System administrators can closely estimate
volumes being replicated and the bandwidth type, the initial
process of creating identical data sets at a remote site can
take weeks or months – an unacceptable timeframe for many
organizations.
FOUR WAYS TO LOWER THE COST OF REPLICATION | WHITE PAPER
Compellent
Portable
Volume
dramatically
shrinks
the
synchronization timeframe to days or hours, regardless of the
type of data link between sites. It jumpstarts replication by
3
SCALABLE SAS: THE BEST OF BOTH WORLDS
Compellent Scalable SAS provides a cost-effective, all-in-one
storage
solution
for
replication
target
sites.
System
enabling users to prime portable, high-capacity hard drives
administrators can establish a remote site with just one
with the volume(s) base and Replay information necessary
controller and one SAS enclosure, then scale up over time to
for the initial synch-up from the source array. The drives are
accommodate growth.
then physically transported to the remote site, where they are
One controller supports as many as 32 enclosures, each with 12
connected to a target array. The Compellent SAN auto-detects
or 24 drive bays, and users can scale from 6 to 384 SAS drives
the Portable Volume and immediately begins the creation of
in a single system. In addition to being highly scalable, unlike
identical replication volumes on the target array.
other SAS solutions on the market, Compellent’s SAS bundles
allow users to mix and match performance-oriented drives and
Businesses that have historically required rapid synchronization
capacity-oriented drives in the same enclosure. The result is an
of critical data previously would have had to send a duplicate
optimal balance of performance and value – a cost-effective,
storage enclosure to their remote locations or invest thousands
stand-alone SAN with the capability to support enterprise-class
of dollars in a separate, dedicated high-speed data link. The
Portable Volume kit, which consists of two 2 TB enterprise-
functionality such as Automated Tiered Storage right “in the
box.”
class external hard drives, two USB cables and a ruggedized
case, presents a far more cost-effective option for creating
deliver rapid replication startups without sacrificing existing
mirror-image data stores within hours or days. This elegantly
FC ports needed for front- or backend connectivity. The data
simple solution enables administrators to implement remote
on Portable Volume drives is readable and visible only to the
replication without the bottlenecks caused by low-bandwidth
Compellent SAN and can be encrypted using standard AES
links or large data stores. In addition, system administrators
128-bit technology for maximum data-at-rest protection during
can replicate data more quickly with Portable Volume than
transit. After synchronization is completed at the remote site, the
with traditional replication running as a background task over
hard drives can be used to initiate replications at other target
a shared link.
sites.
4. Use SAS Strategically at Remote Sites
Typically, performance-oriented FC drives and high-capacity
SATA drives are housed in separate enclosures. This often
results in enclosures that are only half-populated at remote
sites, consuming valuable rack space and driving up the cost
per usable GB for replication targets.
Local
With Compellent Scalable SAS, system administrators can mix
high-performance SAS drives and high-capacity SAS drives in
the same enclosure. The result is an optimum combination of
speed and value with a minimal footprint. High-performance SAS
Remote
Figure 3: Portable Volume jumpstarts replication by using external
enterprise-class hard drives with USB connectivity for initial
synchronization in lieu of duplicate arrays or high-speed data links.
drives are comparable in price to FC drives, but SAS enclosures
and interconnects are less costly than their FC counterparts. In
addition, since Compellent SAS drives are fully interoperable
with FC and SATA drives, all three drive types can be mixed in
the same system for increased remote replication flexibility.
For small to midsize data centers with limited bandwidth, and
for organizations with stringent data availability requirements,
Configuring remote sites with a blend of SAS drives also enables
Portable Volume leverages the common USB 2.0 interface to
system administrators to take advantage of enterprise SAN
FOUR WAYS TO LOWER THE COST OF REPLICATION | WHITE PAPER
functionality like Automated Tiered Storage without FC or
SATA drives. Fluid Data storage classifies the two drive types
into tiers based on capacities and speeds, and uses blocklevel intelligence to automatically migrate data bi-directionally
between the two tiers based on changing access patterns.
This brings a whole new level of efficiency to the utilization of
mixed drives within a single array. By decreasing reliance on
costly drives for replication targets and reducing the number of
drives required, companies can slash overall storage costs by
as much as 80 percent.
3
CONCLUSION
Utilizing Compellent’s innovative replication technologies, it
becomes fully feasible for data centers of all sizes to implement
a business continuity plan that is resilient, robust and sharply
focused on providing high IT impact on a budget. It all begins
with a dynamic, block-level architecture, which provides the
granularity required to create a virtualized pool of storage
resources. Storage virtualization ensures optimal resource
utilization, enabling system administrators to replicate data
efficiently and recover from system failures or natural disasters
For storage administrators who are already performing remote
replication, shrinking the data center footprint with fewer
enclosures can bring cost/benefit ratios in line with tightening
IT budgets. For those looking to implement offsite replication
for the first time, Compellent’s support for SAS makes remote
replication affordable while delivering an unprecedented range
almost instantly. Initial replication synchronization can be
performed in a matter of days instead of weeks or months – all
without expensive, high-speed connections or the need to ship
duplicate arrays from site to site. And Scalable SAS provides
a cost-effective yet high-performance replication target solution
with a minimal footprint.
of enterprise-class features. Either way, an investment in SAS
delivers significant savings in TCO and ensures that current
investments are protected as the industry moves away from
relying on high-cost FC drives.
FC
FC
SATA
SAS
SATA
New York
London
Figure 4: With Scalable SAS, high-capacity and high-performance
drives can be combined in a single enclosure for cost-effective remote
site configurations capable of enterprise functionality.
Compellent Technologies
7625 Smetana Lane | Eden Prairie, MN 55344
877 715 3300 tel | 952 294 3333 fax | www.compellent.com
© Copyright Compellent 2010. All rights reserved. WPREP092010