Monday, 24 September 2007

PSSST....Green Storage

HDS announced today a few amendments to the AMS/WMS range. The most interesting is the apparent ability to power down drives which are not in use a-la-Copan.

According to the press release above, the drives can be powered down by the user as necessary, which presents some interesting questions. Firstly, I guess this is going to be handled through a command device (which presumably is not powered down!) which will allow a specific RAID group to be chosen. Imagine choosing to power down a RAID group someone else is using! Presumably all RAID types can be supported with the power down mode.

One of the cardinal rules about hardware I learned years ago was never to power it off unless absolutely necessary; the power down/up sequence produces power fluctuations which can kill equipment. I'm always nervous about powering down hard drives. I've seen the Copan blurb on all the additional features they have in their product which ensures the minimum risk of drive loss. I'd like to see what HDS are adding to AMS/WMS to ensure power down doesn't cause data loss.

Finally, what happens on the host when an I/O request is issued for a powered down drive? Is the I/O simply failed? It would be good to see this explained as I would like to see how consistency is handled, especially in a RAID configuration.

However, any step forward which makes equipment run cooler is always good.

The announcement also indicated that 750GB SATA drives will be supported. More capacity, less cooling....

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