Odd file system corruption in ZFS pool

[Bob Friesenhahn]

On Wed, 25 Apr 2012, Andrew Reilly wrote:
> from corruption (boot panic loop after a zpool scrub) a year or
> so ago, so the current system is new since then.  The first had
> been upgraded at least once, not sure about the current.  Has
> only ever been attached to this (regularly upgraded) _STABLE
> system.  It isn't protected by a UPS, and the power has been
> going out without warning fairly regularly, so IMO that is
> sufficient to explain the cause of the corruption.  Setting up a
> UPS is my next project.

With properly implemented hardware (i.e. drives which obey the cache 
flush request) it should not be possible to corrupt zfs due to power 
failure.  Some of the most recently written data may be lost, but zfs 
should come up totally coherent at some point in the recent past.  It 
is important to use a system which supports ECC memory to assure that 
data is not corrupted in memory since zfs does not defend against 
that.  Storage redundancy is necessary to correct any data read 
errors but should not be necessary to defend against the result of 
power failure.

Bob
-- 
Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/