ZFS kernel panic after power outage

CyberLeo Kitsana cyberleo at cyberleo.net
Wed Apr 12 15:52:48 UTC 2017

On 04/11/2017 05:38 PM, Jason W. Barnes wrote:
> FreeBSDers:
>     After a recent power outage here I have run into trouble whenever I
> try to mount, or export, or list, or do anything at all to one of my ZFS
> file systems (see attached image).  It instantly goes all "panic:
> solaris assert: rs == NULL".  This is my data drive, not my system
> drive, so I commented out "zfs_enable=YES" in my rc.conf and it will now
> boot up after I set the system drive readonly to "off".  But I'd like to
> now try to recover the damaged file system on those drives.
>     The only think that I can think of, and hope for, at this point
> might be to start unplugging one of this three-drive RAID-5 at a time to
> see if that might cleanse the RAID of something that might have been in
> mid-write when the power went out.  Or that could metastasize the
> cancer. Which would be bad.
>     I've seen occasional posts in the past with similar issues, but
> without any firm solutions, so I thought that I'd ask if anyone has any
> insights as to how I might attempt to recover this drive.  Thanks in
> advance if you have any ideas,

ZFS is self-healing - this makes it extremely robust; unfortunately, 
when problems arise that its self-healing cannot correct, it tends to be 
an extremely dire situation indeed.

Having had a look at the code surrounding the above-mentioned assert, it 
doesn't appear to be easily circumventable for recovery. After making a 
copy of the disks involved just in case, you may attempt to import the 
pool in ZFS-on-Linux or Illumos, to avoid possible implementation bugs, 
or import from an earlier, hopefully-consistent txg; however, I suspect 
that you'll have better luck recreating the pool from backups.

Fuzzy love,

<CyberLeo at CyberLeo.Net>
Technical Administrator

CyberLeo.Net Webhosting

Element9 Communications

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