Tips for Risk-Free Thin Provisioning

Thin provisioning: The term denotes a range of techniques for faking out a storage system in order to avoid overinvesting in disk space. And while vendor argument over the fine points has generated a media hypefest, users seem captivated by the concept of thin provisioning and eager to see if it really works. (See Revisiting Thin Provisioning's 'Firsts' and Real Thin Provisioning.)

Apparently, it does. Companies like Compellent, Datacore, Pillar, and 3PAR credit thin provisioning for increased sales. Among large system suppliers, Hitachi Data Systems has created thin provisioning for its Universal Storage Platform V that's been OEM'd by HP (in its EVA XP24000) and resold by Sun. (See Hitachi Bulks Up and Pillar Pushes Provisioning, Capacity.) NetApp claims to have its own take on the technique for file stores, in addition to a partnership with 3PAR. (See 3PAR, NetApp Join Ranks.) EMC has had thin provisioning for file and iSCSI on EMC Celerra systems since early 2006. And iSCSI vendors are getting in on the act. (See EqualLogic to Add Thin Provisioning and EqualLogic: Thin Is In.)

But thin provisioning comes with caveats. Even David Scott, CEO of 3PAR, has warned users about the importance of monitoring capacity thresholds in any implementation. (See Thin Is Definitely In.) Early adopters say thin provisioning can lead to problems if not done right.

The question is, what constitutes doing thin provisioning right? There are customers who claim to be succeeding with it, including Michigan-based law firm Dickinson-Wright PLLC (an EqualLogic user), Priceline.com (a 3PAR user), European satellite systems operator SES ASTRA (Datacore), the U.K.'s Sunlight Service Group (3PAR), and United Airlines (HDS).

Successful deployments have a few things in common. To find out what these are, we explored the issue with a range of suppliers, experts, and customers, and came up with the following list of thin provisioning best practices:

• Don't believe the hype. "Just because a solution claims to be transparent, doesn't mean it is," says Greg Schulz of the StorageIO consultancy. "The term can mean virtually anything. Ask the vendors what they really do. Make them demonstrate it. See how it scales. If a product doesn't address your particular environment and how you use storage, it's not for you."
• Be aware of architectural differences, but don't prejudge. Vendors differ in their approaches to thin provisioning. 3PAR, for instance, claims to carve physical disk arrays into "chunklets" of storage. Users request a specifically sized volume at a given quality of service, and the system carves out the capacity automatically. The hitch? You need 3PAR's arrays to make it work.