Hitachi Data Systems' Tagmastore can now virtualise IBM's ESS - Shark - storage arrays.

HDS' Universal Storage Platform (USP) can add ESS Model 750, 800 and 800 Turbo drive arrays to its own drives in a single virtual pool of storage. Virtualisation is when all the drives in storage arrays are combined into a single logical pool, allocated as needed to servers and applications. As such, it avoids wasteful over-allocation of disk storage and increases disk use.

Meanwhile, IBM's SAN Volume Controller can now also add in HDS Thunder 9200 and 9500 V Series modular arrays to existing IBM storage that it virtualises into a single pool.

The HDS USP can't virtualise IBM's new DS8000 and DS6000 however, and IBM can't virtualise HDS' Lightning arrays. It looks as if the two vendors are not being that aggressive in virtualising each other's kit.

Tom Hawk, general manager for IBM Enterprise Storage, admitted there was a lot of co-operation going on: "IBM is pleased to work with Hitachi on this interoperability testing for its recently announced virtualisation product. Our work with Hitachi further enhances our strategy to have an open, collaborative approach to storage." That's nice. We look forward to the IBM storage lion lying peacefully down with the EMC storage tiger when it has a cross-vendor array virtualising capability.

As well as the HDS Thunder arrays, IBM's SVC also supports attachments to HP Enterprise Virtual Arrays, IBM’s owm DS8000 and DS6000, and EMC's Symmetrix DMX Series - the DMX800, 1000, 2000 and 3000.

But it can't virtualise HDS' Tagmastore, nor can the Tagmastore virtualise IBM's SVC. If it could then we could envisage ever receding virtualisation systems in which SVC virtualises TagmaStore, which virtualises SVC, which... you get the idea.

The sensible part about virtualising other vendor's arays for both HDS and IBM is that it gives them a chance to get their virtualisation controller into customers' sites with competitors' arrays in place. Once in place, there are then cross-selling opportunities for drive arrays and storage applications using the virtualisation platform.

And that's virtually all you need to know.