Insider's Guide- Building a Virtualized Storage Service
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STORAGE VIRTUALIZATION: AN INSIDER’S GUIDE
Jon William Toigo
CEO Toigo Partners International
Chairman Data Management Institute
Copyright © 2013 by the Data Management Institute LLC. All Rights Reserved. Trademarks and tradenames for products
discussed in this document are the property of their respective owners. Opinions expressed here are those of the author.
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AN INSIDER’S GUIDE
Part 6: Building a Virtualized Storage Service
The dream of every rock star is to create timeless music that garners a
broad audience spanning many generations of fans and evokes wild-eyed
appeals for endless encores. That is the definition of star quality.
Even the most modest IT administrators and planners would like for their
data storage strategies to achieve a kind of timelessness. They want
storage to be more manageable and predictable in terms of cost and
performance – and even power consumption – while delivering
measurable efficiency improvements in every category that matters to
the business they serve. Ultimately, they want to be technology leaders
who deliver improved service levels while cutting costs of operation.
Storage virtualization is a technology that can enable this kind of
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STORAGE VIRTUALIZATION: AN INSIDER’S GUIDE
Building a Virtualized Storage Service
STORAGE AS A SERVICE
In previous sections, we have talked about storage virtualization as a key enabler of storage as a
dependable service to the organization. Storage virtualization delivers improved capacity
management, performance management, data protection management -- and ultimately data
management – by establishing a software layer – sometimes called a storage hypervisor –
above the hardware infrastructure itself. In so doing, storage virtualization translates complex
storage hardware and plumbing into a centrally managed resource that can be allocated
dynamically to business applications and processes.
Implementing a storage hypervisor can have a significant impact in bending the cost curve of
storage hardware infrastructure and the large cadre of staff required to administer and
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maintain it. This is important, especially given the capital and operating expense of storage
Storage virtualization directly addresses the problem of storage infrastructure management
inefficiency by enabling fewer administrators to manage more capacity. A storage hypervisor
addresses high storage product costs by enabling value-add functions to be shared across all
storage rather than being isolated to specific arrays, where they tend to increase the price tag
on each product.
Bottom line: the storage hypervisor makes a simple adjustment to storage infrastructure that
makes it more manageable in operation and less costly to own. Just implementing a storage
hypervisor helps to rectify years of inefficient storage infrastructure design – when we bought
storage arrays with isolated on-array functionality that created massive difficulties in coherent
management and drove up operational costs – and moves us a lot closer to the holy grail of
an efficient and cost-effective storage infrastructure. Moreover, this strategy enables us –
To keep gear in service longer.
To purchase less expensive gear with no sacrifice in terms of either performance or
functionality: services like thin provisioning are extensible to all gear regardless of the
vendor name on the front of the box.
To manage and to administer more capacity with fewer folks.
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To map resources to applications and machines, whether virtual or physical,
effortlessly and to balance workload across gear with minimal intervention.
And to perform machine maintenance with no downtime at all.
In addition to these important operational and financial efficiencies, it should be emphasized
that adding a good storage hypervisor contributes greatly to the safety and protection of
irreplaceable data assets. It simplifies storage and provides flexibility in assigning the right data
protection services to the right data. It reduces the risk of outages due to value-add software
failures on individual array controllers. It enables mirroring and replication without the
constraint of hardware lock-ins that allow replication only between two rigs from the same
vendor. Finally, using a storage hypervisor lets us protect data simply and efficiently without
buying and integrating multiple hardware and software data protection products. That goes
directly to the quality of service guaranty that is only possible with virtualized storage.
Perhaps the greatest contribution of an enterprise class storage hypervisor to Storage as a
Service is its ability to provide predictability in the face of changing technology. Three
contemporary examples help to illustrate this idea:
Support for Server Virtualization
Server virtualization, which began to take hold in enterprise computing environments around
2005, imposed new requirements on storage infrastructure that, arguably, were not foreseen
by many early adopters. The ability to transition workloads between different hosts carried
with it a requirement for storage volumes to migrate with applications themselves. Given the
limited flexibility of “hard-wired” storage fabrics (sometimes called SANs) and their inability to
accommodate such ad hoc data migrations, planners confronted a difficult problem. Did the
adoption of server virtualization necessitate the abandonment of investments in Fibre Channel
fabrics and a return to direct-attached storage?
The good news is that storage virtualization has helped many companies surmount this
problem. With virtualized storage, physical storage infrastructure does not need to change to
accommodate changing workload locations or access patterns. A “virtual volume” containing
the data associated with a virtual machine can “move” with the virtual machine while load
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balancing connections occur behind the scenes. That’s one way that a storage hypervisor
brings flexibility in the face of changing technology.
Support for Desktop Virtualization
Potentially much more important to organizations than server virtualization technology is
burgeoning virtual desktop infrastructure (VDI) technology. Virtualization of desktops, contrary
to its popular interpretation, is not simply about replacing or reducing the cost of physical PCs
and workstations. The physical client device will likely remain in place (with less costly devices
such as terminals and mobile devices such as tablets and smart phones added where needed).
The real benefit of VDI is the centralized hosting and management of desktop software.
The challenge, from a storage perspective, has been how to provision storage resources to
meet such a dynamic and unpredictable workload. Hardware array providers have performed
tests and measurements and concluded that buying “brand X” array would support thousands
of desktops for a much lower price than current desktop equipment. However, this is of little
help to IT managers who seek to deploy VDI in stages – supporting only a few hundred desktops
at a time.
Ideally, planners want predictable cost and performance metrics for VDI so that it can be
deployed incrementally. Using a storage hypervisor, as DataCore Software demonstrated in
2011 in a groundbreaking research and development project, could deliver just such a practical
– and predictable – roll-out model.
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Readers here can find DataCore’s studies on their website. Simplified and condensed, DataCore
offers a hub-and-spoke model called a STAR configuration, that can be used to build out
virtualized storage infrastructure in “atomic units” delivering predictable capacity, performance
While focused on VDI, DataCore’s findings could be applied to the design and implementation
of most multi-user application workloads. This is another way that storage virtualization
provides predictability – a key strategic infrastructure planning value – adding to an already
compelling business and technology value case.
Support for Clouds
Taken individually, server and desktop virtualization may be strategic IT initiatives in many
companies. And, as previously stated, a storage hypervisor can support these strategies by
delivering manageable, flexible and predictable storage resources that can adapt to changing
workload requirements. For many planners, a storage hypervisor is already an essential
component of a software stack that will lead to a virtual data center, or “cloud.”
The bad news is there is competition within the server and desktop virtualization market
among vendors whose products take decidedly different approaches to their task. For example,
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in the server virtualization space VMware competes with Microsoft Hyper-V and
Citrix XenServer for market share.
Competition, while a good thing generally, can (and has) created more complexity and
challenge for those seeking to build private clouds or to leverage public cloud services that
leverage different server or desktop virtualization software stacks. For those firms using
multiple server virtualization products (as well as some non-virtualized servers), the issue has
begun to take on nightmarish proportions as vendor after vendor seeks to add a proprietary
storage hypervisor to its server hypervisor stack. Doing so requires planners to permanently
assign some storage assets just to machines running brand "X" server hypervisors, other assets
to brand "Y" server hypervisor workload, and still others to non-virtualized hosts. Exchanging
information between these isolated stacks, or managing storage itself in the face of such
segmentation, is a daunting challenge.
Public clouds are also beginning to manifest this problem. Sourcing resources from multiple
public cloud service providers increasingly runs afoul of the proprietary virtualization software
stacks used by different providers, significantly impairing the promise of cloud technology to
enable firms to select cloud resources for integration with their own IT infrastructure on an as
needed basis and with assurance that the resources can be used and managed holistically.
This problem underscores another value of a well-groomed storage hypervisor: it should not
only be hardware agnostic, permitting the deployment of any storage gear, but also server
hypervisor agnostic – capable of delivering storage services to any guest machine, regardless of
the brand of server virtualization software it is operating (if any at all). With DataCore
Software’s SANsymphony-V, for example, virtual storage volumes can be delivered on demand
to any and all guest machines, regardless of the server hypervisor that is being used.
SANsymphony-V already offers plug-ins to the management consoles of VMware vSphere and
Microsoft Server and Hyper-V.
In the case of internal clouds, SANsymphony-V provides a “universal bridge” between the
different server virtualization products, empowering planners to select the best server or
desktop virtualization stack for the job at hand, eliminating any sort of lock-in to a particular
server hypervisor’s wares, all without sacrificing management or existing investments in
This ideal of stack agnosticism is being extended to the realm of public clouds as well. The
simple solution to the problem of integrating public cloud storage services would be for every
cloud service provider to simply deploy the same storage hypervisor, such as DataCore’s
SANsymphony-V. That would enable the storage hypervisor to serve as a “Rosetta Stone”
capable of translating disparate resources into a common service.
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However, the real world is a bit more complicated. So, another approach is to use an
intermediary appliance that translates storage at a cloud service provider into a resource that
can be pooled with storage locally virtualized and managed using SANsymphony-V.
DataCore recently partnered with TwinStrata to do just that. The TwinStrata CloudArray
software appliance seamlessly integrates with DataCore SANsymphony-V storage hypervisor.
This bridges SANsymphony-V virtual storage pools to external cloud resources, enabling
organizations to fully manage both private and publicly-sourced storage resources.
The three examples above illustrate how a best-of-breed storage hypervisor can make a
significant contribution to storage efficiency – even in the face of technology change.
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The previous sections of this document have sought to explain why you should consider
virtualizing your storage. All that remains is to provide some guidance for actually doing it.
This is based on the author’s experience in deploying DataCore Software’s SANsymphony-V in
his own company, and also on numerous interviews seeking best practices from other
SANsymphony-V users large and small.
Broadly speaking, getting started means determining which assets of your storage
infrastructure to virtualize first. We could offer guidance that reflects our view of the
limitations and inefficiencies of current storage hardware products, but the best guide may well
be something more simple and practical: payoffs.
Ask yourself, where do you hope to derive the quickest payoffs from virtualizing storage?
Where will storage virtualization success deliver value to you in the form of self assurance or
confidence in the strategy itself? Which parts of your storage infrastructure, when virtualized,
will deliver recognizable improvements in storage services – delivering quick wins and
engendering a better understanding of the broader potential of the technology? What storage
virtualization success will secure for you (and the strategy itself) the approval of those who
keep the budget for an additional investment in a storage hypervisor?
These questions may be difficult to answer without some careful consideration and reflection.
When you have decided, here is one approach you may find useful to start the project.
The good news is that deploying a storage hypervisor may cost you nothing in terms of
hardware. DataCore’s storage hypervisor, SANsymphony-V can be deployed readily using
repurposed servers and existing storage.
1. If you use server virtualization today, consider consolidating two or three physical
servers by consolidating them into virtual machines.
2. Repurpose two of those servers to use as DataCore storage virtualization nodes.
3. Disconnect your direct-attach disks from the apps servers when you have a convenient
planned downtime window and relocate them evenly behind the DataCore nodes.
4. Use the SANsymphony-V pass-through feature to bring those volumes under the control
of the storage hypervisor. No lengthy migration is necessary.
5. Set aside extra disk space to mirror those volumes to the companion node.
6. Mirror the pass-through volumes to the companion node on thin provisioned pools.
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7. Redirect the workloads to the mirrored node.
8. Wipe the original volumes clean and reclaim the space as part of a thin provisioned pool.
9. Re-synchronize the mirrors, now fully virtualized, with any wasted space from fat
10. Take the third server to a remote site as the SANsymphony-V disaster recovery node.
11. Connect the primary site to the DR site over an IP WAN.
12. Make a local clone of the virtual disks you want to replicate remotely using the
13. Ship the clones to the remote site and connect them to the DR node (this is usually
faster than attempting to clone a large amount of data over a WAN link).
14. Turn on the remote replication to keep the DR copies reasonably up to date.
15. Set up Advanced Site Recovery so if you have to switch to the DR site, any updates that
transpire there can later be synched back to the primary site before restoring normal
These 15 steps will get you going on your first implementation of DataCore Software’s
SANsymphony-V. To get another view of what you should expect from this process, you may
want to consult the Lab Validation Report produced by Enterprise Strategies Group (ESG) and
posted on DataCore Software’s website. Their mixed workload benchmarking revealed that a
virtualized environment with the same equipment could handle five times more Microsoft
Exchange users than could a standalone implementation of the application without virtualized
That done, you have taken your first steps towrd a more efficient, more flexible and more
adaptive storage infrastructure. You may not achieve actual virtualization “Rock Star”
status, but you are sure to get requests for many encores in the future.
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