Hitachi Data Systems (HDS) has extended its thin provisioning technology, announced last July only for internal drives in HDS USP arrays, to include third-party disk arrays attached to its USP-V storage array controller.

Thin provisioning - dynamic provisioning is the HDS term - is the technique of allocating a full logical amount of storage (LUN) to an application but only actually dedicating a fraction of that in physical storage terms. As the physical storage is used up to store data, a new set of physical disks can be connected to the virtualising array controller.

It is incorporated in existing storage pools transparently and without disruption to applications. The full LUN allocation is this arrived at in stages.

This avoids having to buy and power up a lot of disk storage 'up front' and thus saves on disk purchase cost and also the disk power and cooling bill as no power is being wasted by spinning empty drives.

What HDS has done is to extend its thin provisioning capability to third-party arrays that can be attached to and managed by the USP-V controller. It now has a uniform, centrally-managed and heterogeneous thin provisioning function.

Previously, third-party arrays could be included in the single logical pool of virtualised storage presented to servers by the USP-V, but not thinly-provisioned. Now they can and users of EMC, IBM and other vendors' arrays managed by the USP-V can defer fully populating them with disks until extra disks are actually needed to store data.

No other drive array and controller supplier has extended its thin provisioning technology to include third-party drive array products.

Claus Mikkelsen, HDS' chief scientist, said: "Only Hitachi can equip customers’ existing storage assets with capabilities they were never designed to encompass, such as thin provisioning, thereby making virtualised storage systems greener, lowering customers’ power and cooling consumption rates and increasing the utilisation of storage capacity."

However, software-only thin provisioning virtualisation products, such as DataCore's SANsymphony, already support thinly provisioning third-party drive arrays.

Since HP and Sun OEM USP-V arrays from HDS it can be expected that their badged USP-V arrays will soon have the thin provisioning capability.

HDS has released IOPS figures showing that its USP-V can achieve more than 4 million I/O operations per second, meaning that it has the processing and bandwidth capacity to cope with virtualising and thinly provisioning external arrays.

The company has shipped more than 7,300 virtualising USP controllers. IBM has shipped over 9,000 SAN Volume Controller (SVC) nodes, the nearest competing product to the USP-V, even though it is an in-fabric and in-band virtualising storage controller rather than one located between the fabric edge and the drive arrays as the USP is.

The SVC, which can also virtualise third-party storage, does not have a thin provisioning function.