As well as bringing out new modular arrays in the shape of the WMS100, AMS200 and AMS500, HDS has introduced the NSC55, a disk storage virtualising appliance. It works with these arrays but is sold separately from them.

The NSC 55, NSC meaning Network Storage Controller, uses the same micro-code as the TagmaStore's virtualising function, the USP or Universal Storage Platform. It has:-

- A crossbar switch architecture
- A parallel design
- NAS blade support
- Logical partitioning
- Replication that is storage-agnostic.

This last point means that users can remotely mirror one storage array to a different vendor's array using the NSC55.

The device comes as a 4U rackmount shelf and can manage up to 16 petabytes of attached and hetergeneous disk storage. Supported vendors include HDS, EMC, HP, IBM and Sun. It's a down-sized and down-priced TagmaStore virtualising device. HDS makes the point that its functionality is working in enterprises today; so this is not a version 1 product.

Jonathan Grantham, HDS' UK sales director, said: "The NCS55 is a completely separate product (from the new modular arrays). It brings down virtualisation to the mid-tier. It has its own internal drive and has exactly the same functionality as the USP. It's USP micro-code in a rackmount box."

With the NSC500 HDS confirms its strategy of placing disk virtualisaton, and services layered on top, at the fabric edge and in front of disk arrays. So far only Sun has supported this strategy. It resells TagmaStore and has its own StorEdge 6920 virtualising mid-range array and controller. This too can virtualise other vendor's arrays.

We expected that Sun might not take the NSC55. Not so. HP will take it too. Grantham said: "Yes, they will, as the SE9925. It integrates completely with the high-end USP product. We think Sun and HP will position it at the bottom end of the enterprise range, rather then the way we position it as the top end of the modular range."

That positioning implies that the middle and bottom end of Hitachi's modular range, currently un-virtualised, may not always be left out. Granthan said: "You may see a mid-range NSC model come down the food chain."

The Sun and HP positioning is helped by the NSC555 having mainframe connectivity. Grantham says that it has FICON and ESCON support. The USP has more capacity and is positioned above the NSC55. Once the NSC55 is maximally configured it can grow no further and customers must use the USP for larger scale requirements.

Another future development is IP storage support, Grantham saying: "We will have iSCSI in the box."

High end AMS coming
The Thunder arrays are being replaced by the WMS and AMS arrays. The WMS100 replaces the 9520, the AMS200 the 9530 and the AMS500 the 9570. This leaves the 9585 still in place. Will it be replaced? Grantham goes so far as to say: "That's a reasonable supposition."

We might therefore expect an AMSxxx to be announced some time ahead, with 'xxx' being some number over 500.

HDS with this announcement emphasises its view that both enterprises and medium businesses will need virtualising arrays, indeed the virtualisation of heterogeneous arrays. Why? HDS's Grantham says: "You don't deploy virtualisation unless there is a big need. In the enterprise area and the high-end modular area the business case is based on simplification." HDS's storage products enable storage, he says, to grow and shrink with business need.

Maybe virtualisation location isn't so relevant
Perhaps we are making too much of the location issue, raising too much steam when asking should the V-box be in the fabric or closer to the disk arrays beyond the fabric. After all, starting from the disk arrays there is a connection to the V-box. It could be a SCSI link into the NSC55 or equivalent box. Or it could be a Fibre Channel link, based on SCSI, to a V-box in the fabric. This fabric box could be part of a director or a separate fabric appliance.

Either way, the V-box has to 'see' all the storage attached to it. This is a bigger issue, possibly, than asking whether it has a non-fabric or fabric link to the arrays it virtualises.