Analysis

posted on 09 April 2008 13:43

Xiotech's Emprise Intelligent Storage Element (ISE) is a sealed canister of disk drives with dual controllers providing RAID functions, cacheing and super-diagnostics. In fact it is a nearly complete mini-drive array.

The ISE has either ten 3.5-inch Fibre Channel drives or twenty 2.5-inch Fibre Channel drives in it. It could hold SATA or SAS drives and even solid state disks (SSD) in future.

The controllers implement Seagate's own drive test and re-mediation software so that it can reinstate drives that have suffered a recoverable error or reinstate a failed drive with an error on only one platter by preventing future writes to that platter of the drive but continue using the others.

The controllers implement 520 byte blocks and not the ordinary 512 byte ones with the extra 8 bytes, Data Integrity Bits (DIF), used for data checking information. An EMC blogger says that EMC's Clariion arrays have used DIF from way back when.

Currently all drive arrays use disk drives in 3.5-inch format as their standard, Lego, building block. The Emprise arrays from Xiotech use ISEs. The Velocity1000 arrays from Atrato also use sealed canisters but not in the same format as Xiotech's.

If there were a standard sealed disk drive canister format then drive array manfacturers - Dot Hill, EMC, HDS, HP, IBM, LSI Logic, Xyratex and others - could think seriously about using sealed canisters as their building blocks as they wouldn't be limited to a single source.

Will the disk drive and drive array manufacturers come up with their equivalent of a shipping container standard for sealed canisters of disks? I don't think so.

Perhaps Atrato or Xiotech will open source their sealed canister designs and cancel their patents. Perhaps pigs will fly.

^{[Chris Mellor.]}