Re: linux disk access when idle

[Goswin von Brederlow <goswin-v-b@web.de>]

Tapani Tarvainen <raid@tapanitarvainen.fi> writes:

> Just a data point: I've got a box (Debian Lenny) with five disks,
> system disk plus 4-disk RAID5 array, used as a backup server
> (rsnapshot), and I power the disks in the raid array down after
> running the backup - and they stay powered down, even though I don't
> umount the filesystems let alone stop the array. When accessed (like
> for restoring something from the backup), they wake up, so I've got an
> hourly cron job powering them down again - but most days (when
> there're no restores) they are powered up only during the backup run.
>
> So it can be done. It's not filesystem type dependent either, there's
> one jfs and one ext3 in the array.
>
> The system disk stays up, though. Some experimenting suggested
> that getting it to stay down would require putting /tmp and parts
> of /var on a ramdisk (/var/log at least), but I didn't go to
> the trouble of tracking down all disk-awakening services.

Same here. I have a raid1 for the system on 2 drives and a raid5 over
6 drives for data. The raid5 is ext3 powers down after 15 minutes
without access. The raid1 stays up all the time due to /var/log/syslog
being written to too often. /tmp is tmpfs though.

MfG
        Goswin