Sunlight Service Group

With vendors ramping up their thin provisioning strategies, users are starting to discuss the benefits and challenges of the technology. (See EqualLogic to Add Thin Provisioning and Hitachi Bulks Up.)

The technique, which is being adopted by more and more storage vendors, aims to ensure that physical disk capacity is only used as it is needed. (See 3PAR Debuts 'Thin Provisioning' and A Data Reduction Dossier.) EMC, for example, is planning to deploy thin provisioning on higher end SAN boxes, joining a growing list of vendors that includes 3PAR, LeftHand Networks, Compellent, HP, and NetApp. (See LeftHand Adds 10-GigE SANs, LeftHand Secures $25M, VeriStor, Compellent Team Up, and Cardinal Uses CommVault, NetApp.)

One user with extensive experience of thin provisioning is Najeeb Ahmad, technical projects and support manager at U.K.-based Sunlight Service Group, a supplier of textile rental and laundering services, which deployed a 9.5-Tbyte S400 system from 3PAR last year. (See 3Par Shines at Sunlight.) "The benefit of thin provisioning is that you can allocate the storage as and when you need it -- there's a lot of wastage with the traditional approach," he says.

Sunlight was on the lookout for something to replace a 2.5-Tbyte MSA device from HP and also support major server consolidation. "If we didn't have this in place, we wouldn't be able to contemplate [the consolidation]," says Ahmad, explaining that the firm is cutting back from 120 to 50 HP ProLiant servers.

Specifically, Sunlight can now provision storage for these servers in a matter of seconds, a process which otherwise would have taken a couple hours.The exec admits that despite the performance benefits promised by thin provisioning, the technology also poses unique challenges. Even vendor 3PAR, for example, recently highlighted the importance of setting disk capacity thresholds and alerts for when these limits are about to be reached. (See Thin Is Definitely In.)

Sunlight's Ahmad warns that IT managers are looking for trouble if they ignore this issue, which he has solved using 3PAR's own software. "If you're not clever with how you set it up, it would be possible to let all the servers that connect to the SAN take up all of the [disk] space," he says. "Technically, you can massively over-commit your resources."

Other users are dipping their toe into thin provisioning. New York-based Grey Healthcare Group, for example, has just bought a 20-Tbyte iSCSI SAN from EqualLogic, and is planning to roll out thin provisioning on the system sometime in the next 60 days. (See EqualLogic Enhances Program, iSCSI Gang Talks Big, and EqualLogic Provides Solution .)

The issue of thresholds is not exactly keeping Grey's IT director Chad Sutton up at night. "We centralize management of the storage, so that individual departments can't allocate that themselves," he says.

Specifically, Grey is using interfaces within EqualLogic's own software to control access. "As long as you have one or two people that have their hands on the system," he says, "all the allocation of the disk is handled at a high level."Analyst Jon Toigo of Toigo Partners International foresees a broader challenge for firms considering thin provisioning, particularly when it comes to interoperability with existing Storage Resource Management (SRM) products such as TekTools' StorageProfiler and CA's BrightStor. (See Tek-Tools Releases Module and CA Widens SRM Support.) "The [thin provisioning] vendors say we have tools that will show you the [disk] capacity, and that's true, but you're not able to see that through third-party tools," he says.

There has been some movement in this area, such as 3PAR working with SRM specialists CreekPath and AppIQ, although Toigo thinks that in general interoperability efforts have been limited. (See 3PAR Debuts Native SMI-S and 3PAR, AppIQ Form Storage Alliance.) "In a heterogeneous environment where you use multiple vendors' gear [thin provisioning] stands in the way of a clear view of what your capacity is at any given time," he says.

James Rogers, Senior Editor Byte and Switch