[Please cc xfs@xxxxxxxxxxx on XFS bug reports. Added.] On Wed, Jan 26, 2011 at 08:22:25PM -0500, Mark Lord wrote: > Alex / Christoph, > > My mythtv box here uses XFS on a 2TB drive for storing recordings and videos. > It is behaving rather strangely though, and has gotten worse recently. > Here is what I see happening: > > The drive mounts fine at boot, but the very first attempt to write a new file > to the filesystem suffers from a very very long pause, 30-60 seconds, during which > time the disk activity light is fully "on". Please post the output of xfs_info <mtpt> so we can see what you filesystem configuration is. > This happens only on the first new file write after mounting. > From then on, the filesystem is fast and responsive as expected. > If I umount the filesystem, and then mount it again, > the exact same behaviour can be observed. I can't say I've seen this. Can you capture a blktrace of the IO so we can see what IO is actually being done, and perhaps also record an XFS event trace as well (i.e. of all the events in /sys/kernel/debug/tracing/events/xfs). > This of course screws up mythtv, as it causes me to lose the first 30-60 > seconds of the first recording it attempts after booting. So as a workaround > I now have a startup script to create, sync, and delete a 64MB file before > starting mythtv. This still takes 30-60 seconds, but it all happens and > finishes before mythtv has a real-time need to write to the filesystem. > > The 2TB drive is fine -- zero errors, no events in the SMART logs, > and I've disabled the silly WD head-unload logic on it. > > What's happening here? Why the big long burst of activity? > I've only just noticed this behaviour in the past few weeks, > running 2.6.35 and more recently 2.6.37. Can you be a bit more precise? what were you running before 2.6.35 when you didn't notice this? > * * * > > The other issue is something I notice at umount time. > I have a second big drive used as a backup device for the drive discussed above. > I use "mirrordir" (similar to rsync) to clone directories/files from the main > drive to the backup drive. After mirrordir finishes, I then "umount /backup". > The umount promptly hangs, disk light on solid, for 30-60 seconds, then finishes. Same again - blktrace and event traces for the different cases. Also, how many files are you syncing? how much data, number of inodes, etc... > If I type "sync" just before doing the umount, sync takes about 1 second, > and the umount finishes instantly. > > Huh? What's happening there? Sounds like something is broken w.r.t. writeback during unmount. Perhaps also adding the writeback events to the trace would help understand what is happening here.... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
