Ceph » Linux kernel client

On Wed, 16 Jun 2010, Peter Niemayer wrote:

Hi,

trying to "umount" a formerly mounted ceph filesystem that has become
unavailable (osd crashed, then msd/mon were shut down using /etc/init.d/ceph
stop) results in "umount" hanging forever in
"D" state.

Strangely, "umount -f" started from another terminal reports
the ceph filesystem as not being mounted anymore, which is consistent
with what the mount-table says.

The kernel keeps emitting the following messages from time to time:

Jun 16 17:25:29 gitega kernel: ceph: tid 211912 timed out on osd0, will
reset osd
Jun 16 17:25:35 gitega kernel: ceph: mon0 10.166.166.1:6789 connection
failed
Jun 16 17:26:15 gitega last message repeated 4 times

I would have expected the "umount" to terminate at least after some generous
timeout.

Ceph should probably support something like the "soft,intr" options
of NFS, because if the only supported way of mounting is one where
a client is more or less stuck-until-reboot when the service fails,
many potential test-configurations involving Ceph are way too dangerous
to try...

Yeah, being able to force it to shut down when servers are unresponsive is
definitely the intent. 'umount -f' should work. It sounds like the
problem is related to the initial 'umount' (which doesn't time out)
followed by 'umount -f'.

I'm hesitant to add a blanket umount timeout, as that could prevent proper
writeout of cached data/metadata in some cases. So I think the goal
should be that if a normal umount hangs for some reason, you should be
able to intervene to add the 'force' if things don't go well.