Thin provisioning storage brings utilization and capacity benefits, but with a caveat

Introducing thin provisioning technology into existing and new enterprise data storage environments can bring dramatic storage recovery rates and bottom-line savings. The technology works in disparate environments with a wide range of storage capacity and application needs, and can help many administrators solve the ongoing dilemma of provisioning enough storage to each application so it can run smoothly while still retaining enough storage to introduce new applications and deal with unexpected growth. Major vendors have been slow to offer thin provisioning technology, however, perhaps because they were reluctant to reduce the amount of capacity (and products) their customers must buy.

Despite its benefits, thin provisioning storage has its drawbacks. A thin provisioned system has to be monitored more than a typical storage array because the potential harm caused by disk or system failures is higher. In a typical array, if you exceed capacity on one or even two disks, the remaining disks can compensate and allow applications to run unimpeded. A thinly provisioned system simultaneously pools storage from multiple disks and manages multiple applications, so one failure can bring down the house. You can address the problem with rigorous system monitoring, but it likely remains a deterrent to the technology's adoption at many IT organizations.

But a Storage magazine Storage Priorities survey on enterprise data storage fielded in the fall of 2008 found interest in thin provisioning slowly increasing. Of the 208 respondents, 13.5% had implemented thin provisioning, an increase of 3% from the 2007 survey. Another 20.7% planned to deploy the technology in 2009 (up 9.9% from the previous year), while 34.6% said they would evaluate thin provisioning in 2009. Yet 31.3% of those surveyed said they had no plans to implement or evaluate the technology in 2009 vs. 47.7% in 2008.

Capacity allocation and storage provisioning easier to manage

When a new application is installed in an IT environment, the storage administrator must dedicate enough capacity to that application to allow it to run well as it grows, which typically means overprovisioning the storage. According to Mark Peters, a senior analyst at Milford, Mass.-based Enterprise Strategy Group (ESG), applications require a lot of capacity up front but rarely use what they get. "Most of us have grown up in a world where you ask for more than you need so that you make sure you get your bit," Peters said. "And then you don't use it."

Thin provisioning storage allows administrators to virtually dedicate the amount of data storage the application requires, but allocate storage to the application only when it writes data, so it uses only what it needs. The remaining storage is held in a pool for other uses.

The benefits of allowing storage administrators to pool and use their storage capacity instead of reserving it and letting it sit are obvious. The organization can install and run more applications with less capacity; storage administrators can initially buy less equipment, which means less power, less cooling and less floor space; and IT can delay capacity purchases, which means they'll most likely be able to purchase disks at lower cost.

As mentioned above, the benefits of thin provisioning come with a price tag -- increased system monitoring. All of the technology's advantages won't mean much if you run out of capacity and every application linked to the thin-provisioned capacity shuts down in mid-operation. According to Jeff Boles, senior analyst and director, validation services at Hopkinton, Mass.-based Taneja Group, the more applications and data you tie into the technology, the more you have to lose. "Thin provisioning has to be monitored and managed on an ongoing basis," he said. "And if you do so, the payoff can be enormous. But without monitoring, if you run out of capacity in the platform, things can certainly fall apart, and they'll probably fall apart in different ways depending on the array."

Long-term planning is essential. Today's popular server consolidation projects can depreciate the benefits of thin provisioning. "If you plan to do lots of consolidation and have runaway growth, you should have a serious focus on how far your storage platform will scale," Boles said. Filling up a thin provisioned array with consolidation data or rapidly accumulating data cancels the technology's benefits because you wouldn't pre-allocate space for that data.

Despite these caveats, some IT organizations, are using thin provisioning to dramatically increase their storage utilization rates, while others are using it to gain flexibility in their storage provisioning.

Vendors bow to pressure and add thin provisioning

According to ESG's Peters, large storage industry vendors have mixed feelings about technologies that allow people to reduce how much storage they have to buy. "Thin provisioning isn't good when you're trying to sell volumes and volumes of storage, and more and more capacity," he said. "It's not intrinsically attractive to the big incumbent vendors."

But the success of smaller vendors such as 3PAR Inc. and Compellent Technologies Inc. put pressure on large vendors to acknowledge and offer thin provisioning. "It requires all of an industry pushing in a certain direction for a technology to become pandemic," Peters said. "And it's taken some of the bigger companies a long time to get there."

While there's often disagreement about who did what first, Brian Garrett, vice president, ESG Lab, said 3PAR was the first company to make thin provisioning viable in the marketplace. The company's very first press release in May 2000 references thin provisioning as a "green technology developed to address storage underutilization and inefficiencies." Compellent and LeftHand Networks Inc. (now part of Hewlett-Packard Co.) were also early proponents.

Almost every major storage equipment vendor now offers thin provisioning products. IBM announced the addition of thin provisioning to its System Storage DS8000 and XIV Storage System in July. EMC Corp. first offered its Virtual Provisioning technology in its Symmetrix DMX line in January 2008, Hitachi Data Systems introduced thin provisioning in its Universal Storage Platform V (USP V) series in 2007, and NetApp Inc. unveiled its FlexVol storage virtualization in November 2004.

3PAR and Symantec Corp. have established a partnership to usher in "the next step in thin provisioning," which includes easier data migration from non-thin provisioned (or "fat") volumes to thin provisioned volumes, and easier capacity reclamation when data is deleted from thin provisioned volumes. Compellent touts its similar Thin Import technology for simplified data migration, as well as its Free Space Recovery technology for data reclamation in Windows environments. Hitachi announced similar technology in June 2009 with its Zero Page Reclaim technology to recover unused storage blocks.

Thin provisioning storage features: Factors to consider

According to ESG's Peters, there are three factors to consider when evaluating storage array thin provisioning features:

1. Data "chunks." According to Peters, the foremost difference between the thin provisioning technologies offered by the major vendors is how they provision each chunk of data. Craig Nunes, 3PAR's vice president of marketing, said his company's 16 KB chunks are the smallest in the market. Other vendors believe the size isn't as important as the efficiency. Hitachi Data Systems' USP V system parses storage in 32 MB chucks, which the company claims is more efficient in storage layout and cache memory. When deciding on a product, make sure you're comfortable with how your thin provisioning system slices and dices your data.

1. Import ability. Do the systems you're considering easily take fat data and make it thin? If you plan to migrate a significant amount of data from your legacy storage system to a thin provisioned system, research how each vendor accomplishes this task. Also ask for references from customers that have faced the same issues.

1. The GUI. How easy is it to manage the system? Does it use the same alerting methods you use (such as email or text messages), and are the right people alerted at the right time when your thin provisioned system nears capacity? If not, your applications may stop running right when your CEO is posting photos from his kid's first birthday party on Facebook. Heads will roll.

Peters said the biggest bang for your buck will occur when you make the jump to thin provisioning, not if you switch from one implementation to another. The technology itself provides immediate benefits, and the major vendor implementations will vary only slightly. He likens it to switching from a horse and buggy to a combustion engine -- that's how dramatically your storage environment may change. After adopting thin provisioning, the difference between vendors is similar to those between V6 and V8 engines. Either way, you'll be running faster and more efficiently than ever.