Comment Slim down those controllers! A return to thin controller arrays is being advised by Xiotech, which wants us to get away from the current 'fat controller' syndrome.

The idea is that too much functionality has been pushed down the storage stack and both modular and monolithic arrays now do fancy things like zero space reclaimation, thin provisioning, data tiering, snapshotting, cloning and replication - on top of what Xiotech says are the three basic array functions of storing, protecting and moving data.

Its chief technologist Steve Sicola - a man who delights in upsetting established applecarts - says this only happened because server and software operating system vendors were hooked on open, non-proprietary systems, and encouraged array vendors to implement the functonality so as to avoid adding proprietary storage features to their O/S software.

But along comes VMware and starts adding its own top-level storage functions to its hypervisor that duplicate what storage arrays now do. You can have VMware thin-provision your storage or have a VMware-connected 3PAR array do it, or both. Sicola would say this is ludicrous and the array should just stop doing things that are better done, and are being done, higher up the stack by hypervisors or apps like Symantec's FileStore.

That way the array controller gets simpler, its maintenance easier and it can concentrate all its CPU cycles on doing the basic store, protect and move operations better.

Well, we might think, Sicola would say that as he has his sealed disk canister ISE technology and there's no space for fat controllers inside the ISE storage bricks. On top of that Xiotech is not a major array controller, in fact we could with candour say it is, in effect, pretty much a me-too array vendor, and so can differentiate itself by junking the fat controller idea, and enabling faster and easier links between the upper levels of the storage stack and ISE bricks and brick collections.

That's what the CorteX API is, with its fashionable RESTful interface. The thing is so simple and lightweight Xiotech has a demo of an iPhone App using it to query and manage an Emprise 5000 array of ISE bricks. Data centre admins will just love managing their ISE storage from a beach in Hawaii, for sure.

The question is, is Xiotech right? Obviously EMC, Dell, HP, IBM and other fat controller array-producing giants are not going to agree, not with a marketing stance put out by a re-energised small storage vendor with a brand new management team and a storage technology featuring nice bells and whistles, but which has struggled for years to get established.

Xiotech and its channel have to deliver ISE kit to customers that does as it's told by VMware, XEN, HyperV, FileStore and whatever other apps decide to run storage directly, and does it faster, more simply, more reliably and much less expensively than the equivalent CLARiiON, EVA, whatever array.

Sicola would say it doesn't matter what the storage giants say; the hypervisors and the FileStore-type apps are going to be the first tier of storage management and array producers have just got to fit in because that's the entry ticket for playing in a hypervisor's backyard. The issue is not going to be a theoretical 'who's right' one but a more practical one; can an ISE brick collection do the storage job for a hypervisor significantly better than traditional storage array vendors?

In fact I'd guess Xiotech doesn't actually much care if the fat control functions are done higher up the stack or not, not when push comes to shove. Ask yourself what would happen if EMC decided to build its CLARiiON replacement using ISE bricks, with the CLARiiON controller telling the bricks what to do. Xiotech would say, that's a terrific idea, sign here and tell us how many thousands of ISE you want and where they should be delivered.

It's not really about the fatness of controllers, arguably; it's more about taking cost out of arrays and increasing their performance and reliability.

Xiotech has a convenient and quite distinctive marketing stance, which is good news for a smallish array supplier fighting giants many, many times its size, but its success will depend not on winning an intellectual debate, but on an energised channel shipping very cost-effective boxes. Ask Compellent about that. ®