* Theodore Tso <tytso@xxxxxxx>: > On Wed, Feb 25, 2009 at 10:31:42AM -0600, Eric Sandeen wrote: > > > > It'd be better to get to the bottom of the problem ... maybe iostat > > while it's happening to see if IO is actually happening; run blktrace to > > see where IO is going, do a few sysrq-t's to see where threads are at, etc. > > > > Can you find a way to reproduce this at will? > > > > Journal replay should *never* take this long, AFAIK. > > Indeed. The journal is 128 megs, as I recall. So even if the journal > was completely full, if it's taking 800 seconds, that's a write rate > of 0.16 Mb/S (164 kb/second). That is indeed way too slow. The problem seems to be with the external journal which I recently changed to. It's a 32GB partition. My timings seem to indicate that ALL OF IT was being replayed > I assume this wasn't your boot partition, so the journal replay was > being done by e2fsck, right? Yes > Or are you guys skipping e2fsck and the journal replay was happening > when you mounted the partition? Both. We tried both ways :) > If the journal replay is happening via e2fsck, is fsck running any > other filesystem checks in parallel? No, it's running alone. > Also, what is the geometry of your raid? How many disks, what RAID > level, and what is the chunk size? The journal replay is done a > filesystem block at a time, so it could be that it's turning into a > large number of read-modify-writes, which is trashing your performance > if the chunk size is really large. The RAID is made up from one logical volume, consisting of two drives sda and sdb, each containing 6 disks in a hardware RAID5 setup. > The other thing that might explain the performan problem is if the > somehow the number of multiple outstanding requests allowed by the > hard drive has been clamped down to a very small number, and so a > large number of small read/write requests is really killing > performance. The system dmesg log might have some hidden clues about > that. dmesg is silent -- Ralf Hildebrandt Ralf.Hildebrandt@xxxxxxxxxx Charite - Universitätsmedizin Berlin Tel. +49 (0)30-450 570-155 Geschäftsbereich IT | Abt. Netzwerk Fax. +49 (0)30-450 570-962 Hindenburgdamm 30 | 12200 Berlin _______________________________________________ Ext3-users mailing list Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
