Date: Thu, 10 Apr 2014 09:24:10 -0500 From: dweimer <dweimer@dweimer.net> To: FreeBSD Questions <freebsd-questions@freebsd.org> Subject: ZFS can't destroy snapshot, dataset busy Message-ID: <5fe3d5f142b1646768b3528206e6dd36@dweimer.net>
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I have a server running on ZFS, with multiple jails. I use bacula to
back it up, and have written a python script that finds all my ZFS
datasets (except those I have listed to ignore) and creates snapshots,
then mounts those snapshots to a temporary file structure, using mount
-t nullfs /zfs-mountpoint/.zfs/snapshot/snapshotname /mnt/backup/... I
then backup the data from the snapshots, and kick off a second script
that dismounts the nullfs mounted snapshots and destroys them. I have
the same script running on multiple servers without jails and everything
works great.
However on this server that is running 4 jails, (base OS is FreeBSD
10-RELEASE-p1, as of last night) the root file system in the jails is
frequently holding the snapshots as busy so they fail to destroy, which
then breaks the backups for that jail until resolved.
The only resolution I have found do an unmount -f
/zfs-mountpoint/.zfs/snapshot/snapshotname and then I am able to destroy
the snapshot. The nullfs mounts are gone, but I haven't been able to
find what process is holding onto the snapshot file system.
Before I edit my script to add this step in prior to destroying the
snapshots, does anybody have any ideas on how to find out whats keeping
these file systems busy?
I have already tried restarting the jail using jail -r and jail -c it
doesn't help, its something in the base Operating System
--
Thanks,
Dean E. Weimer
http://www.dweimer.net/
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