Curious failure of ZFS snapshots

Gerrit Kühn gerrit at pmp.uni-hannover.de
Fri Nov 21 06:15:25 PST 2008


On Fri, 21 Nov 2008 13:39:20 +0000 Pete French
<petefrench at ticketswitch.com> wrote about Curious failure of ZFS snapshots:

PF> On the box with the snapshots being created every day with the same
PF> name I quickly end up with unavailable snapshots, and the error
PF> message: 'Bad file descriptor'. On the machine which is creating
PF> dailys which do not have the same name this does not happen.
PF> 
PF> Interesting - and unexpected. The machines are running identical
PF> kernels, being 7-STABLE form a few days ago.

I have a similar setup (creating daily.0 every night and rotating the
rest) for some home directories here...
Right now 3 of them are fine, and one is showing the same problem you
described:

mclane# ll /tank/home/pt/.zfs/
ls: snapshot: Bad file descriptor
total 0


Note that zfs still thinks the snapshots are there:

mclane# zfs list -r tank/home/pt
NAME                    USED  AVAIL  REFER  MOUNTPOINT
tank/home/pt            454M  1.78T   262M  /tank/home/pt
tank/home/pt at weekly.1  32.5M      -   260M  -
tank/home/pt at daily.6   29.6M      -   262M  -
tank/home/pt at weekly.0  45.3K      -   262M  -
tank/home/pt at daily.5   45.3K      -   262M  -
tank/home/pt at daily.4   28.2M      -   262M  -
tank/home/pt at daily.3   28.7M      -   262M  -
tank/home/pt at daily.2   27.8M      -   262M  -
tank/home/pt at daily.1    374K      -   262M  -
tank/home/pt at hourly.7  45.3K      -   262M  -
tank/home/pt at hourly.6  45.3K      -   262M  -
tank/home/pt at hourly.5  45.3K      -   262M  -
tank/home/pt at hourly.4  45.3K      -   262M  -
tank/home/pt at daily.0   45.3K      -   262M  -
tank/home/pt at hourly.3  45.3K      -   262M  -
tank/home/pt at hourly.2  45.3K      -   262M  -
tank/home/pt at hourly.1  45.3K      -   262M  -
tank/home/pt at hourly.0  45.3K      -   262M  -


I even do autoamtic incremental backups via send/receive. There are no
errors (up to today) and the snapshots are accessible on the backup
machine.

I am a bit troubled by unaccessible snapshots. Does anyone else here have
the same problem (or can even offer a solution)?


cu
  Gerrit


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