Comment 0 for bug 1071733

we're using LVM snapshots on our storage server to provide data for our live and staging instances.
there are two mountpoints on the server, one for the origin volume, and one for the snapshot that are exported using NFS to our live/staging instances (webserver)

today i noticed, that writes on our staging-webserver don't go to the snapshot as expected, but are hitting the origin volume, messing up all of our live data.

i checked the NFS-mounts and -exports and they look perfectly valid (staging mounts snapshot-mountpoint, live mounts origin-mountpoint)
on the storage-server itself looking at the mountpoints, everything looks valid, too. i wrote some identifying test-files in each mountpoint in order to track them. no problem as long, as we look on the NFS-server itself.

but looking in the mountpoints of a NFS-client, it shows that the origin data was mounted.
i found no way to mount the snapshot again.

i'm not entirely sure, what component causes the problem. since the mountpoints look valid on the server itself, i would rule out LVM. i also would rule out the NFS-client, since it should not be able to see what the server hasn't exported. all clients can see the problem (lucid, maverick, precise).

i've checked for recent software-upgrades on the NFS-server and found:

Thu, Oct 25 2012 11:07:16 +0000

[INSTALL] linux-image-3.2.0-32-generic:amd64
[UPGRADE] nfs-common:amd64 1:1.2.5-3ubuntu3 -> 1:1.2.5-3ubuntu3.1
[UPGRADE] nfs-kernel-server:amd64 1:1.2.5-3ubuntu3 -> 1:1.2.5-3ubuntu3.1

Fri, Oct 26 2012 09:29:34 +0000

[UPGRADE] linux-generic:amd64 3.2.0.31.34 -> 3.2.0.32.35
[UPGRADE] linux-image-generic:amd64 3.2.0.31.34 -> 3.2.0.32.35

since it was working as expected before thursday (2012-10-25), i downgraded these packages (and rebooted the older kernel)
this didn't solve the problem.

i can reproduce this behavior using different filesystems on the NFS-server.

i'll attach verision info in my next post. please comment on what info you might need to figure this out.