Storage virtulisation unmasked

Virtualisation has become the tabloid story of the data storage industry - hot, controversial and everywhere. BRETT WINTERFORD tries to separate the virtual from the reality.

Virtualisation is a concept created by the data storage industry to describe new ways of masking the complexity of storage environments. It's about managing all of your various physical storage devices - be they RAID arrays, disk drives or tape drives - as a single pool of storage.

The concept has seen a good deal of hype in the tech press. In the words of one industry guru, storage virtualisation has become "centre square in buzzword bingo". And for good reason: implemented in its ideal form, storage virtualisation lowers IT management costs and makes life considerably easier for administrators. But the problem for resellers looking to invest their skills in virtualisation is that you are likely to get a different answer on how to go about it from just about every vendor you talk to.

Traditionally, storage assets have been attached and assigned to individual servers to cater for specific applications. Every server typically had its own attached storage.

"You may have had two servers for two different applications - one with 10 per cent utilisation, one with 100 per cent, but you still had to buy more storage for the device that was running out of space," Network Appliance marketing director, Mark Heers, said.


A far more efficient use of resources is to have a single pool of storage that all servers can share. Virtualisation refers to the abstraction layer that enables these disparate storage resources to appear as one virtual pool in a management console.

"With virtualisation, you are able to just use the total pool until it is full, and add more disk as you need it," Heers said.

Virtualisation has many benefits for IT administrators. At the physical level, it addresses the disparity between the actual storage capacities of devices and the requirements of individual applications. Typically, storage hardware has a greater capacity than what is required by an individual application.

"Before virtualisation, you might have purchased three years worth of your storage needs for the life of a project," Symantec technology specialist, Mark Read, said. "A lot of the capacity would just be sitting there, consuming power, taking up space in the data centre until such time as it would be needed. With virtualisation, somebody else within the organisation might be able to use that capacity until such time as you need it."

Virtualisation provides administrators with a macro view of a single virtual resource, masking the complexity of the many physical assets that make up that resource. Ideally, it should enable administrators to migrate data from one system to another without too much staff involvement.

Analyst group, Gartner, suggests that without virtualisation, one administrator is able to manage up to around 300GB of data; whereas in a well-executed virtualised environment, that person could manage up to 2TB.

"People are the most expensive asset in a data centre," Enstor managing director, Terry Semple, said. "Virtualisation can lead to enormous cost savings from that perspective. With the proper set-up, you could manage five or ten times the same capacity of storage with the same amount of people." It also allows organisations to define policies which link the importance of data with the performance and cost of the medium it is being stored on. Using tools that analyse types of data and their value to the business, data can be allocated in a tiered fashion. Critical data can be stored on high performance, expensive disk while data that has become less critical is stored on cheaper media.

Examples of such policies might include transferring data that has not been used or accessed for six months to cheaper disk, or permanently storing the files of high-ranking executives on high performance disk. These policies can also determine where data is stored according to file type - for example, bulky video files might be considered too expensive to use on high performance disk and be relegated to cheaper media.

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It also allows an organisation to avoid vendor lock-in. The data storage industry is infamous for its heterogeneity and has sprawled in many proprietary directions. While industry bodies such as the Storage Networking Industry Association (SNIA) are making some efforts to introduce open standards, organisations often find themselves locked in to the products of single vendors.

An abstraction layer that allows for ubiquitous access to the storage capacity of all of these different vendor products is seen as a means of avoiding such limiting scenarios.

"Virtualisation enables you to manage many different storage products on one console," IBM storage business unit executive, Francois Vazille, said. "It gives you flexibility in which disk hardware you want to use."

In its ideal form, the complexity of the storage environment is also transparent to the user. "All the user might notice is a small amount of extra time to access that data," Symantec's Read said.

While there is little argument over the benefits of virtualising storage resources, there is a good deal of conjecture in the market as to where in particular the technology should be deployed. Host-based virtualisation sees the abstraction layer deployed on the server, network-based virtualisation sees it deployed in the switch, while array-based virtualisation sees the technology limited to the storage device itself.

Proponents of host-based virtualisation argue that it is the best way to effectively virtualise storage resources across multiple hardware platforms. "You have the freedom to swap and change hardware," Read said.

As larger organisations increasingly deploy Storage Area Networks (SANs) to manage their resources, networking vendors such as Brocade argue the technology should be deployed in the switch.

"Specifically compared to host-based solutions, consolidating storage virtualisation functions in the storage network can greatly reduce the instances and versions of software that need to be deployed and managed," Brocade product marketing manager, Mario Blandini, said. "Rather than managing multiple versions of software across many server touch points and multiple operating systems, switch-based applications enable central management of a single application version.

"Centralisation makes management easier, and also provides increased capabilities in that any server with a SAN connection can use the virtualisation services, not just the operating systems for which the host-based software is available."

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But some vendors, such as HP, say that organisations can derive just as much benefit from virtualising across the drives in a single storage array. "SAN-wide virtualisation appears to be the utopia customers are interested in," storage marketing manager for HP, Mark Nielsen, said. "But that's only relevant for a small number of very large organisations that have multiple arrays from multiple vendors."

"We tend to break it off into chunks that people can actually use," he said. "It shouldn't just be a technology for high-end customers."

But network-based virtualisation vendors and niche virtualisation vendors such as Falconstor argue that the limited functionality of RAID controllers should not be called virtualisation, and that such simplification is blurring its definition. Semple argues that all the vendors have different approaches, and whether they are appropriate depends entirely on the needs of an individual customer.

"There is no underlying panacea," he said. "All the vendors have a part of the puzzle."

In order to bring the pieces of the virtualisation puzzle together, there are increasing calls for the development of storage standards that will future-proof customer investments.

The standards proposed thus far had not been adopted by the whole industry, Sun Microsystems storage and data mananagment practice manager, Dan Kieran, said.

There had been a number of examples of market-leading vendors releasing products based on proprietary technology that had inevitably been abandoned as the rest of the industry matured a standard, Kieran said. "Customers get left hanging."

"As a customer I wouldn't want to go near anything that doesn't comply with SNIA standards," he said.

But the standards effort is missing its share of big league storage players, and even integrators such as Enstor suggest that SNIA is still a long way off having anything concrete.

Semple said all a customer could do when choosing a solution was to analyse what vendor products were already in use within the organisation and make inquiries as to what virtualisation products work for the majority of them.

"Not all the virtualisation products will work with all hardware platforms," he said. "It's important as integrators that we keep up to date on this."

Because of the large amount of integration work required to make storage virtualisation a reality, there is a lot of opportunity for channel partners with integration or development skills. Sales director of storage integrator Tripoint Corporation, Nigel Peach, there were many storage companies in the industry selling individual components that make up a storage virtualisation solution but very few have the ability to put the building blocks together.

Semple said margins were being squeezed on storage hardware products, and to a lesser degree on software, but integration skills were still in high demand. Neither vendors nor customers tended to have the skills or the tenacity to take on such integration work.

"IT administrators don't have the integration or SAN-specific skills to do it alone, whereas we are rolling out 20 and 30 SANs a month," he said.

"These things are complex and the level of consulting required is massive. Vendors don't tend to understand their competitor's products very well, to our benefit," he said.

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Several broad-based storage vendors are looking to push the virtualisation concept into the mid-market, an area where the channel has traditionally held the vital customer relationships.

"Companies with 250-odd employees have started deploying virtualisation," IBM storage executive, Francois Vazille said. "We are relying on our channel partners to promote the technology in the medium sized business space. For resellers, virtualisation can be a key differentiator."

But while there are opportunities, entry into the market is far from easy. The storage channel is made up of specialist providers who have a couple of decades head start in storage networking skills.

Enstor's Semple said too many resellers entered the market tied to one particular vendor, and found it difficult to win over customers due to their lack of focus or vendor neutrality. Channel players would also need to consider the complexity and skill levels required to pull off a project.

"There is not a good appreciation out there of the time, effort and money it takes to deploy this technology," Semple said. "The results are great, but you have to expect to have some pain along with it."

"I have seen a lot of cases where companies have spent seven figure sums on an infrastructure refresh, but it's had zero impact on profit and loss," agreed Peach.

"Virtualisation is not the solution unto itself, it is only an enabler," Sun's Kieran said. "Too many people are focused on the technology and not what they are trying to achieve or address."