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Networked storage: Virtualization tall on promises, short on delivery

Contributor Johanna Ambrosio addresses virutalization in this edition of TechTarget's Information Architect.

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Networked storage: Virtualization tall on promises, short on delivery

But analysts agree that while this fast-growing market is chaotic, now is the time to learn about this fledgling storage technology.

By Johanna Ambrosio, contributor

Enterprise storage requirements are growing at 50% each year, according to a Forrester Research report. Companies facing that type of runaway growth -- as well as any other firm fighting with ever-expanding storage needs -- are well-advised to look at virtualizing their storage to help manage it all.

"Larger-scale storage users, specifically with heterogeneous needs, are the primary users" of this technology, says Steve Duplessie, a senior analyst at the Enterprise Storage Group in Milford, Mass. "These are primarily customers with large, Fibre Channel-based SANs that are interested supporting different vendors' storage devices and perhaps different operating environments in the same SAN." Other primary targets include dot-com companies that provide services akin to application service providers.

Virtualization is the process of taking many different physical storage networks and devices and making them appear as one "virtual" item. Primary benefits include: easing the management of a bevy of individual storage boxes -- particularly for global companies with far-flung IT resources; the ability to mix and match different vendors' storage products as well as products of different capacities and speeds; and the ability to create, expand or delete a virtual storage drive by using extra capacity on different physical devices.

That's the promise, anyway. The reality of today's products is far different from the ultimate vision, some observers warn. There are no real standards, and vendors are implementing their own versions of virtualization software and/or hardware that emphasize ease of management, speed or some number of the benefits of the technology over the others.

"It's something that has been co-opted by various marketing organizations to mean what they want it to mean -- and the result is an awful lot of confusion," says John Webster, a senior analyst with Illuminata Inc. in Nashua, NH.

That's something to be aware of when shopping for virtualization-related products and services, Webster warns. He likes to think of virtualization as "a process, on one hand, and the results of a process on the other hand. Where the process is relatively easy to define, the results are varied -- and that's where the confusion comes in."

Dan Tanner, a senior analyst at the Aberdeen Group in Boston, recently wrote a report in which he said pretty much the same thing. He defines virtualization as something that makes "programming and operation simpler by automating resource management housekeeping" for storage -- similar to how an operating system works for a computer system. "When this process occurs," Tanner writes, "computer users are said to be viewing resources 'at a higher level of abstraction.'" So, he says, virtualization is really the "abstraction of storage."

That stated, there's one key problem, according to Tanner. "Virtualization that will meet this goal of abstraction and serve as the key enabler for policy-based storage management is not yet widely available."

Even with this confused state of affairs, it's not too early to begin learning about storage virtualization and the ways it might apply to your company. It's only a matter of time before the reality ultimately catches up to the hype, many observers believe.

There are three places you can work this process of taking physical devices and presenting them to an application as a virtual entity. The first is in the storage device itself, such as with a storage array. The second is at the host end.

Alternately, the virtualization can happen somewhere in between the storage device and the host -- with an intelligent appliance, for example, that sits somewhere between the host bus adapter and the array. Or the virtualization can also happen within a network-attached server device.

"There are lots of different ways to do this," Webster says. All the virtualization products and architectures have various advantages and disadvantages, he says, and "all produce varying sets of results." It just depends on how companies want to use them.

When looking at the various products available, organizations "should carefully consider potential storage virtualization benefits, whether the solution is scalable, and if it is able to work with legacy equipment and support managing multiple storage area networks centrally," Tanner's report says.

Another factor, Webster says, includes latency -- how long it takes to get the data that the user or application requests.

Also, it's important to spend some time to understand how the specific solution you're looking at actually works, particularly around the issues of data flow and meta-data, Webster says. "It's important to understand how this works to help understand the issues of latency and scalability," he says.

Issues that will be key going forward include "file systems and databases and how they fit into these virtualization schemes," Webster says. It is possible to pool or aggregate storage through virtualization, but the underlying data can't truly be shared unless there's an underlying file system that allows this to happen, he adds.

Vendors in the virtualization space thus far include EMC Corp. in Hopkinton, Mass.; StoreAge Networking Technologies Ltd. in Scottsdale, Ariz.; Kom Networks Inc. in Monterey, Calif.; Tricord Systems Inc. in Plymouth, Minn.; Vicom Systems Inc. in Fremont, Calif.; Storage Technology Corp. in Louisville, Colo.; XIOtech Corp. in Eden Prairie, Minn.; Veritas Software Corp. in Mountain View, Calif.; DataCore Software Corp. in Ft. Lauderdale, SanOne Inc. in Phoenix, Ariz.; Compaq Computer Corp. in Houston, Texas; IBM; and Hewlett-Packard Co.

About the author:
Ambrosio is a freelance writer in Marlborough, Mass.; write her at


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This was last published in July 2001

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