On Wed, 01 Jul 2009 12:32:20 +0530, Shehjar Tikoo <shehjart@xxxxxxxxxxx> wrote: > Furthermore, all writes are forced to disk at a close(). Hmm, that could be it. But would this not be caught by the usual write delaying functionality in laptop_mode? >> I find that if I put the server into "laptop mode" to conserve power >> by spinning down the disk writes still tend to wake them up. > > Are you sure they're writes and not reads? Anything is possible, but I have lots of RAM in this server and have 4MB of read-ahead set, followed by head -c1 on every file to pre-buffer everything. In that state I wouldn't expect the disks to ever spin up except to write out the data every 10 minutes. > And are you sure it is > GlusterFS process that is issuing requests that need service from disk? I'm not 100% sure at the moment. It could also be gluster's logging since it's going raw rather than through syslog. >> Are the any particular paramters/options that should be used in this >> mode to minimize disk wake-ups? Disable direct I/O? Does write-behind >> work for local disks? Any suggestions on this? > > 1. Try spinning down without GlusterFS running. See if the disk still > wakes-up. It is possible a different application wakes up the disk. > > 2. With glusterfsd running, try unmounting all the mount points to > this server and leave the server running. It might help us pin-point > if the server is issuing disk requests without us knowing about it. > > 3. Keep GlusterFS server running along with all the mount points > mounted. But do not have any applications running on the mount points. > This will help us determine if the GlusterFS client side stack is > issuing disk requests even though no application requests are coming > through. OK, I'll try all that and report back. I'll also apply the patch I posted here: https://bugzilla.redhat.com/show_bug.cgi?id=223722 and see if that helps. Gordan
