Re: [gentoo-user] How can I power disk off?

[Paul Hartman <paul.hartman+gentoo@gmail.com>]

On Thu, Oct 6, 2011 at 2:44 PM, Mark Knecht <markknecht@gmail.com> wrote:
> Paul,
>   Would hdparm be advisable if the drive was part of a RAID? I suspect not.
>
>   I don't think this applies to the OP but for the sake of discussion
> why not include RAID as part of the solution, if possible.

I use hdparm to set power-saving on all members of my RAID5 and it
works (in my case, I'm setting them to never spin-down). I created a
file /etc/local.d/hd-power-level-fix.start containing one line:

hdparm -B 254 /dev/sd[abcdef]

which automatically sets those drives to never spin down.

In my original recommendation, I hadn't considered hdparm's "spindown
immediately" option. I was thinking of the -B command like I used
above, to adjust the "spin down after X idle time" option. If all
members of the RAID have the same idle time they'll probably all spin
up and down together under normal usage (well, depending what kind of
RAID it is, I suppose). In my case, I found the "click, whirr, click,
whirr, click, whirr, click, whirr, click, whirr" waiting for 5 disks
to spin-up when I accessed the RAID annoying, so I disabled it. (I
have not done any power-consumption measurements to see what that's
costing me...)