Storage Virtualization: Its Changing Definition.

There could be a huge gap between promise and performance

If you were to turn the clock back one year and do a survey of companies offering storage virtualization products, you would be lucky to find three. Yet, a quick web search today would yield an overwhelming number of hits for "storage virtualization". Why the big spike? Either a lot of companies spent a lot of R&D funds on this secret sauce, or the definitions have changed. It's probably a little bit of both.

Confounding this metamorphosis is the fact that there's a huge gap between what some vendors say they'll deliver, and what end users actually get. This article explores some of the key issues and questions around virtualization to help end users ascertain if the products they're considering constitute true virtualization. If nothing else, a suggested "litmus test" should help weed out those who merely masquerade as virtualization solutions.

Interpreting The Signals

Accept for a moment that the excitement from users around storage virtualization is well founded. Generally the vendor community jumps on a technology trend bandwagon for one of three reasons: They invented it; they see opportunity in it, or they're threatened by it.

As a company considering virtualization, it's important to read between the lines to determine the orientation of the advocate. For example, those dominant vendors most threatened by a technology are most likely to define a long list of desirable features not likely to be achieved in our lifetimes. While this allows them to share in the limelight, it also has the effect of postponing buying decisions until that vendor can come around with an alternative. On the other hand, vendors that invented the innovative technology and their immediate followers may have more genuine interest in having the approach validated, and can point to live customers taking advantage of its benefits today.

The Bottom Line: Economics

Evaluating virtualization alternatives can be relatively easy: it boils down to a few key questions. But in larger enterprises, getting buy-in from the decision-makers on a relatively new methodology may be the bigger challenge.

At the end of the day, it's not the techno-jargon that will convince the holders of the purse strings to move to virtualization--they either want to know what the solution will save them, or how it will make them money. With virtualization at the advent of widespread acceptance, only experienced suppliers are in a position to quantify the economic consequences of a virtualized environment.

To ensure tangible benefits, companies assessing a virtualization solution should look for return on investment (ROI) and total cost of ownership (TCO) analyses that can distinguish the financial projections from competing approaches. It soon becomes clear that only advanced virtualization alternatives can combine savings in time and labor, reclaimed opportunity costs, and enhanced application performance, to defend their compelling claims.

Who are the immediate beneficiaries? While virtualization brings wide range operational and economic value to an organization, it stands to deliver the most significant time and effort savings to system administrators and, indirectly, to the business applications they control. To the system administrator, ideal virtual disks can be reassigned effortlessly from a central location without making time-consuming physical modifications to the hardware or disrupting running applications. To the user or application, a virtual disk appears to be an ordinary local disk. The better virtualization choices make this ordinary disk perform extraordinary feats with substantially faster response.

The result? A storage infrastructure that shields applications from the day-to-day storage management dynamics-sparing end users downtime and I/O delays, while eliminating much of the labor-intensive handholding that would be required without it.

The Span Of Virtualization

Given the growing concern over information asset protection, can a company look to virtualization to assist it in business continuance and disaster recovery across distant sites? In some cases, the answer is a definite "yes".

With the proliferation of remote and mobile workers and their data scattered among multiple sites, it becomes increasingly important for virtualized environments to span the scope of a company's network-be it a campus, a state, a distant branch. Virtualization has no reason to be confined to a box or a room. In fact, it should supply affordable redundant copies of vital information in separate locations for consistent access to the same data by any number of authorized users. Virtualization should be independent of the LANs, WANs, and SANs that link storage farms together. That is the whole idea behind divorcing the applications from the storage hardware.

Is It file Sharing?

The subject of networks brings up another source of confusion: the distinction between block virtualization and file sharing. Sometimes these activities are pitted as competitors when they are complementary. Storage virtualization has generally been associated with the handshake between computers and disk blocks. Most users, on the other hand, deal with file names and shared folders, completely unaware of the translations taking place on their behalf.

Some companies redefine file sharing as a virtualization offering, when in fact, file sharing is simply one of many applications that can benefit from a virtualized pool of disk resources. Therefore, it would not be unusual to see a collection of Network Attached Storage (NAS) filers running alongside database servers and messaging applications, being fed by a common virtual disk pool. At the end of the day, all these "servers" need well-behaved disk supplied to them on-demand by the block virtualization facility.

Impersonators Or Impostors: Don't Get Locked In

Think of virtualization as a layer that insulates applications from the undesirable characteristics of mixed disks, arrays, host bus adapters and even fancy storage controllers. Ideally, one would be able to change the underlying hardware on either side of this divide and continue business as usual, regardless of the brand of hardware and its technology base.

Using this model, the introduction of a different server supplier and a different operating system should not compromise a company's ability to take advantage of a virtualized storage pool. Even opting for a different make of host bus adapters should be inconsequential.

With some virtualization alternatives, there is a real danger of being locked in to specific hardware suppliers and costly capital equipment contracts. In effect, such approaches depend on proprietary characteristics intended to perpetuate a vendor's hardware product lines. This can severely limit a company's choices, and negotiating power, when the next buying cycle comes around.

Sometimes, suppliers cloud the lack of openness under the guise of certificationin other words, if the other platforms that a customer wants to virtualize don't have the brand sticker or proprietary certification, it is forbidden from playing in the virtualization scheme.

Virtualization should imitate disks. No special rules required. If the virtualization choice that a company is considering is imposing new rules, new certifications, and new stickers, it could be just an impostor.

Virtualization For All?

Though the definition of virtualization is somewhat diluted, all evidence points to the beginnings of its broad-based acceptance as a viable technology.

At its best, virtualization leverages all of a company's storage investments, delivers enormous savings in time, labor, and management required to administer storage, and provides scalability and flexibility for change and future growth.

When a data-driven company with a mix of storage hardware in place faces a serious increase in the volume of information it stores, the time is right to consider virtualization. Indeed, because of virtualization, companies have new options available today that manage their storage more simply and demonstrate a very healthy benefit to their bottom line.

Augie Gonzalez is the director of product marketing at DataCore Software (Fort Lauderdale, FL).