January 28, 2004, 2:25 PM — SATA disks are fuelling the advent of disk-to-disk backup with its elimination of the backup windows and virtually instant restore. SATA disks are also used to store fixed content data as with EMC Corp.'s Center and Storage Technology Corp.'s BladeStore. But SATA disks' reliability is a concern and an array of hundreds of spinning disks is not cheap. Think of all those power supplies cables, cache memory and controllers needed for each drive.
A U.S. company called Copan Systems Inc. has a new spin on this. Treat the disk drives as tapes in a library and only have them powered up when needed, hence the massive array of idle disks idea. A Copan array will contain hundreds of trabytes of disk in a single cabinet (think bladed disks). Copan
claims it will be able to offer disk backup at tape prices because of the savings involved.
The many hundred disks share a power supply/controller/cabling cabinet infrastructure.An algorithm is used to decide which disks in a cabinet should spin and which not. Inactive disks are powered down, and then spun up again when needed. Reactivation typically takes under 10 seconds. Disks are spun on a regular basis even when not used to keep them operational.
This so-called duty cycle management can reduce the number of stops experienced by a drive by a quarter. For comparison a typical ATA drive is built for 40,000 stops over its life.
Randy Kearns, a partner at the Evaluator Group, says, "They're really creating a disk library instead of a tape library. You spin them up and use them when you need them, just like tape."
There will be some form of RAID-like scheme to recover from disk or data loss. MAID arrays will be used to store fixed content data as well as backup sets, according to Copan. They wont quite be MAIDS of all work.
StorageTek is also apparently talking about a hybrid disk and tape unit. MAID products are appearing in the U.S. now. It will take some months and some courageous resellers before they become available in the U.K. When they do, remember, you read it here first.
