ZFS Snapshots Not able to be accessed under .zfs/snapshot/name

[Shane Ambler]

On 14/08/2013 22:57, dweimer wrote:
> I have a few systems running on ZFS with a backup script that creates
> snapshots, then  backs up the .zfs/snapshot/name directory to make sure
> open files are not missed.  This has been working great but all of the
> sudden one of my systems has stopped working.  It takes the snapshots
> fine, zfs list -t spnapshot shows the snapshots, but if you do an ls
> command, on the .zfs/snapshot/ directory it returns not a directory.
>
> part of the zfs list output:
>
> NAME                        USED  AVAIL  REFER  MOUNTPOINT
> zroot                      4.48G  29.7G    31K  none
> zroot/ROOT                 2.92G  29.7G    31K  none
> zroot/ROOT/91p5-20130812   2.92G  29.7G  2.92G  legacy
> zroot/home                  144K  29.7G   122K  /home
>
> part of the zfs list -t snapshot output:
>
> NAME                                            USED  AVAIL  REFER
> MOUNTPOINT
> zroot/ROOT/91p5-20130812 at 91p5-20130812--bsnap   340K      -  2.92G  -
> zroot/home at home--bsnap                           22K      -   122K  -
>
> ls /.zfs/snapshot/91p5-20130812--bsnap/
> Does work at the right now, since the last reboot, but wasn't always
> working, this is my boot environment.
>
> if I do ls /home/.zfs/snapshot/, result is:
> ls: /home/.zfs/snapshot/: Not a directory
>
> if I do ls /home/.zfs, result is:
> ls: snapshot: Bad file descriptor
> shares
>
> I have tried zpool scrub zroot, no errors were found, if I reboot the
> system I can get one good backup, then I start having problems.  Anyone
> else ever ran into this, any suggestions as to a fix?
>
> System is running FreeBSD 9.1-RELEASE-p5 #1 r253764: Mon Jul 29 15:07:35
> CDT 2013, zpool is running version 28, zfs is running version 5
>


I can say I've had this problem. Not certain what fixed it. I do 
remember I decided to stop snapshoting if I couldn't access them and 
deleted existing snapshots. I later restarted the machine before I went 
back for another look and they were working.

So my guess is a restart without existing snapshots may be the key.

Now if only we could find out what started the issue so we can stop it 
happening again.