Hi, On Fri, 2009-10-30 at 19:27 -0400, Allen Belletti wrote: > Hi All, > > As I've mentioned before, I'm running a two-node clustered mail server > on GFS2 (with RHEL 5.4) Nearly all of the time, everything works > great. However, going all the way back to GFS1 on RHEL 5.1 (I think it > was), I've had occasional locking problems that force a reboot of one or > both cluster nodes. Lately I've paid closer attention since it's been > happening more often. > > I'll notice the problem when the load average starts rising. It's > always tied to "stuck" processes, and I believe always tied to IMAP > clients (I'm running Dovecot.) It seems like a file belonging to user > "x" (in this case, "jforrest" will become locked in some way, such that > every IMAP process tied that user will get stuck on the same thing. > Over time, as the user keeps trying to read that file, more & more > processes accumulate. They're always in state "D" (uninterruptible > sleep), and always on "dlm_posix_lock" according to WCHAN. The only way > I'm able to get out of this state is to reboot. If I let it persist for > too long, I/O generally stops entirely. > > This certainly seems like it ought to have a definite solution, but I've > no idea what it is. I've tried a variety of things using "find" to > pinpoint a particular file, but everything belonging to the affected > user seems just fine. At least, I can read and copy all of the files, > and do a stat via ls -l. > > Is it possible that this is a bug, not within GFS at all, but within > Dovecot IMAP? > > Any thoughts would be appreciated. It's been getting worse lately and > thus no fun at all. > > Cheers, > Allen > Do you know if dovecot IMAP uses signals at all? That would be the first thing that I'd look at. The other thing to check is whether it makes use of F_GETLK and in particular the l_pid field? strace should be able to answer both of those questions (except the l_pid field of course, but the chances are it it calls F_GETLK and then sends a signal, its also using the l_pid field), Steve. -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
