On Thu, May 04, 2006 at 04:59:33PM -0700, David Kirchner wrote: > Here's how to reproduce the snapshot deadlock I'm seeing, with 6.1-RC2 > cvsup'd as of 5 or 6 hours ago: > > 1) dd if=/dev/zero of=/usr/bigfile bs=1024 seek=209715200 count=0 > 2) mdconfig -a -t vnode -f /usr/bigfile > 3) bsdlabel -w md0 auto > 4) newfs -U md0a > 5) fsck -v /dev/md0a # ^C this after a second or so, this makes the FS dirty > 6) mount /dev/md0a /mnt > 7) fsck -v -B /dev/md0a > > in another window: > 8) while true; do ls -al /mnt/.snap;sleep 1;done > > It locks up every time for me, with no further disk activity. > Unfortunately, for some reason, my server console became unaccessable, > so I'm not able to get to the kdb prompt. If I can get to it later, > what should I run other than "show lockedvnodes" and "show threads"? > Also, can anyone else try these steps and verify if they cause the > same problem for you? I repeat you recipe on CURRENT. What I got was the completely unresponsively system, that was _not_ deadlocked. It has slowly made a progress. Slowness is surely related to hole in the file backing fsck'ed (and snapshotted) filesystem. Snapshotting slowly made a progress, with lot of disk activity. After it had finished, system resumed normal operation.
Tor Egge committed several fixes into CURRENT, that certainly help in this situation. > > In my initial tests, filed in a PR, steps #1 and #2 were unnecessary > as I was working with real disks. The result is the same here. Still, > I am curious if anyone else can get the same result with a real disk > >=200GB in size. I am unable to duplicate it with a 20GB partition, > and I am not sure why. > > -- > David 'dpk' Kirchner
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