On Wed, Aug 06, 2008 at 02:23:44PM -0400, Will Murnane wrote:
> On Wed, Aug 6, 2008 at 13:57, Miles Nordin <[EMAIL PROTECTED]> wrote:
> > If that's really the excuse for this situation, then ZFS is not
> > ``always consistent on the disk'' for single-VDEV pools.
> Well, yes.  If data is sent, but corruption somewhere (the SAS bus,
> apparently, here) causes bad data to be written, ZFS can generally
> detect but not fix that.  It might be nice to have a "verifywrites"
> mode or something similar to make sure that good data has ended up on
> disk (at least at the time it checks), but failing that there's not
> much ZFS (or any filesystem) can do.  Using a pool with some level of
> redundancy (mirroring, raidz) at least gives zfs a chance to read the
> missing pieces from the redundancy that it's kept.

There's also ditto blocks.  So even on a one vdev pool you ZFS can
recover from random corruption unless you're really unlucky.

Of course, this is a feature.  Without ZFS the OP would have had silent,
undetected (by the OS that is) data corruption.

Basically you don't want to have one-vdev pools.  If you'll use HW RAID
then you should also do mirroring at the ZFS layer.

Nico
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