EMC refreshed its entire family of storage arrays earlier this month, but said it would not introduce eagerly awaited thin provisioning features into its Symmetrix and Clariion products until the first half of 2008.

July’s upgrades added support for 4Gbit/s Fibre Channel (FC) and low-cost 750GB Sata II hard drives plus performance improvements to its storage operating systems.

Although EMC first implemented thin provisioning in its Celerra products about a year ago, aimed primarily at small to medium-sized enterprises (SMEs), the vendor publicly stated that it is not yet ready to extend the technology to its corporate-class Symmetrix and Clariion arrays.

Thin provisioning, which helps storage administrators reduce the cost of adding and managing extra data storage capacity, has already found its way into disk arrays from many of EMC’s rivals, including Hitachi Data Systems, HP, Sun, NetApp and 3PAR.

The technology limits over-provisioning by allowing IT administrators to present applications with virtual, rather than physical, storage resources, automatically allocating extra virtual capacity on demand and sending alerts when more physical capacity needs to be added.

Companies only need to add extra hard disks when they actually need them, so over-utilisation is minimised and money saved because extra drives and arrays can be brought at a later date, usually when price erosion means they are cheaper.

“EMC typically does not pre-announce, so it is interesting to note that it has announced thin provisioning,” said David Hill, an analyst with The Mesabi Group. “Symmetrix customers would not want to rush into a decision on thin provisioning anyway, but this lets them get started on planning.”

EMC’s director of storage product marketing, Peter Lavache, said that it is important that EMC takes the time to build in thresholds and triggers to make sure its arrays can grow capacity safely.

“Thin provisioning is just one feature, and we want it to work with different types of workload profiles, as well as local and remote replication – you cannot have one feature break the other features you are already using,” Lavache explained.

Sue Clarke, senior research analyst at Butler Group, said that using thin provisioning can achieve cost savings by delaying essential capacity purchases for as long as possible.

“From the discussions we have had with our subscribers, it seems that they can make savings if they buy disk capacity at certain times of the year, like the end of the sales quarter,” Clarke explained.