IBM has added thin provisioning to its storage portfolio, but not on its DS8000 storage arrays as expected. IBM decided instead to offer thin provisioning on its SAN Volume Controller (SVC) storage virtualization appliance first.
Thin provisioning is among the enhancements IBM rolled out today for SVC 4.3, along with space-efficient FlashCopy (snapshots), virtual disk mirroring (the ability to store two copies of a virtual disk on different systems), and support for Windows Server 2008, Mac OS X and Pillar Axiom arrays.
Thin provisioning improves storage utilization by more effectively allocating disk space. 3PARdata helped make the feature popular, and the larger storage vendors have been adding the feature to their arrays over the last year or so.
IBM calls thin provisioning Space Efficient Virtual Disks, and executives have promised to add it to their high-end DS8000 line to keep up with the industry trend. While adding it to SVC is a twist, it is not unexpected. In a blog on IBM's website in April, Barry Whyte, of the SVC development team, disclosed thatSVC would have thin provisioning, although it wasn't clear if that would come before or after the feature was available on the DS8000.
Chris Saul, IBM's SVC marketing manager, said IBM will incorporate thin provisioning on its storage arrays, but put it in SVC first to enhance the management features of the virtualization product. He said SVC makes thin provisioning available on any vendor's array virtualized by SVC.
"SVC takes control of storage and where it is used," Saul said. "The thin provisioning takes place in SVC, and SVC takes over the customer's storage. A user could install SVC in front of an EMC Symmetrix, for example, and then use SVC to virtually provision all capacity inside the Symmetrix system."
Similarly, Hitachi Data Systems' USP-V high-end storage arrays can thin provision volumes on other vendors' storage attached to its virtualization controller.
Joseph Zhou, senior analyst for Ideas International, said the most interesting thing about IBM's thin provisioning is its pricing. While most vendors charge a licensing fee for thin provisioning, IBM will make it available for free with SVC, which begins at $50,000 for a two-node cluster.
"Not every vendor is providing thin provisioning for free," Zhou said. "Thin provisioning is often charged with a capacity-based pricing scheme. That wipes away the cost savings you get from improving resource utilization."
However, Zhou doesn't expect customers to buy SVC just for thin provisioning. "I don't think the thought process will be, 'I want to add thin provisioning, so I have to buy SVC,'" he said. "I don't think they want to add another layer to their infrastructure just to add thin provisioning. But thin provisioning is becoming an industry standard capability on storage platforms, and customers will expect it pretty soon from all the major vendors."
Saul said IBM has more than 4,000 SVC customers, and it's becoming much more common for them to use it to virtualize storage from different vendors. That makes it more valuable to have thin provisioning available for all of the storage that SVC manages.
"We're starting to see more customers deliberately implementing a mix of storage types so they can have tiered storage," he said. "In the past, people talked about that, but it seemed like it was too complicated to do."
Lifestyle Family Fitness is one example of that. Mike Geis, director of IS operations, said he bought an IBM DS4700 last November to store information on the health center chain's 2,000-plus customers and added a two-node SVC cluster so he can continue to use his four-year-old EMC Clariion CX300 for Tier 2 and Tier 3 storage.
"All of our nodes have the option to use storage on either SAN," Geis said. "It's transparent to the storage systems. SVC presents storage and LUNS without differentiating. We also used SVC to upgrade from SQL 2000 to SQL 2005, and we could use both SANs for flexibility during the transition."
Storage virtualization can still be complicated, though. According to Geis, it makes it harder to find help – either staff or outside consultants – with proper experience. "It's a specialized area of expertise right now," he said. "Not every other storage guy out there has experience with storage virtualization."