From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tapani Tarvainen Subject: Re: linux disk access when idle Date: Sat, 22 Aug 2009 08:04:17 +0300 Message-ID: <20090822050416.GA9202@musti.tarvainen.info> References: <20090820163522.GA29215@sewage> <4A8F190B.9010406@tmr.com> <20090821231039.GB22331@sewage> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20090821231039.GB22331@sewage> Sender: linux-raid-owner@vger.kernel.org To: linux-raid List-Id: linux-raid.ids 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. -- Tapani Tarvainen