It's an old story: Manual provisioning of storage is a source of tension between storage and application folks,...
and contributes to the poor capacity utilization that persists in many storage area networks (SANs).
Those on the application side usually ask for more capacity than they need, says Craig Nunes, senior director of marketing at SAN array maker 3PAR, Fremont, CA.
"The application guy thinks, 'If I get 500GB, I'll never need to take down my application,'" says Nunes. Storage admins, meanwhile, try to put off unnecessary disk purchases and push to allocate less than they're being asked for. In the end, the application usually wins out. In Nunes' experience, applications typically get 75% more capacity than they use.
To this end, 3PAR users can license Thin Provisioning, which presents an application with a virtual volume of arbitrary size, but only allocates physical capacity to it as data is actually written. LeftHand Networks also supports this concept, says Tom Major, the firm's VP of marketing, although it doesn't have a name for it.
Last month, DataCore announced an auto-provisioning feature for users of its SANmelody software, which works across DataCore Networked Managed Volumes on heterogeneous Fibre Channel and IP-based SAN arrays.
Network Appliance's new FlexVol feature, part of its new Data Ontap 7G operating system announced in November, is also a thin provisioning product, says Mike Fisch, director of storage and networking at Wellesley, MA-based Clipper Group. Thin provisioning, he says, is "anything that presents a volume bigger than the capacity it uses and can then fill that capacity."
For its part, EMC is working on what it calls "oversubscribed volumes." A company spokesperson says customers "are interested in this feature because it has the potential to address two issues: reducing storage costs by increasing storage utilization, and minimizing the reprovisioning effort." EMC plans to include the technology across its portfolio, including Symmetrix, Clariion, Celerra and Storage Router.