Caveat emptor: Beware of ZFS on HEAD

From: Peter Wemm <peter_at_wemm.org>
Date: Wed, 12 Jul 2017 13:20:55 -0700
We mostly run HEAD in the freebsd.org cluster.  Sometime in the last few weeks 
an ugly zfs problem has surfaced. If a redundant volume is degraded, zfs 
panics on boot.  If a drive fails while running, or is manually put offline, zfs 
panics the same way.

I do not have a smoking gun, but I am suspicious of the June 28th commits 
(starting at r320156) and their follow-ups. eg: r320452.

https://bugs.freebsd.org/220691

I believe single disk systems will *not* be affected by this - the panic only 
happens when a raidz (and presumably mirror) degrades.  Your laptop etc should 
be fine.

I apologize for being vague - I do not know more. Folks running HEAD should 
take appropritate precautions (eg: keeping a known-good kernel.old and modules 
around).  This is always advisable when running HEAD anyway, particularly so 
now.  For us, a kernel.old from June 18th worked fine.

-- 
Peter Wemm - peter_at_wemm.org; peter_at_FreeBSD.org; peter_at_yahoo-inc.com; KI6FJV
UTF-8: for when a ' or ... just won\342\200\231t do\342\200\246
Received on Wed Jul 12 2017 - 18:20:57 UTC

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