Richard Elling wrote:
Will Murnane wrote:
On Wed, May 20, 2009 at 12:42, Miles Nordin <car...@ivy.net> wrote:
"djm" == Darren J Moffat <darr...@opensolaris.org> writes:
djm> a) it was highly dangerous and involved using multiple
djm> different zfs kernel modules was well as
however...utter hogwash! Nothing is ``highly dangerous'' when your
pool is completely unreadable.
It is if you turn your "unreadable but fixable" pool into a
"completely unrecoverable" pool. If my pool loses its log disk, I'm
waiting for an official tool to fix it.
Whoa.
The slog is a top-level vdev like the others. The current situation is
that
loss of a top-level vdev results in a pool that cannot be imported. If you
are concerned about the loss of a top-level vdev, then you need to protect
them. For slogs, mirrors work. For the main pool, mirrors and raidz[12]
work.
There was a conversation regarding whether it would be a best practice
to always mirror the slog. Since the recovery from slog failure modes is
better than that of the other top-level vdevs, the case for recommending
a mirrored slog is less clear. If you are paranoid, then mirror the slog.
-- richard
I can't test this myself at the moment, but the reporter of Bug ID
6733267 says even one failed slog from a pair of mirrored slogs will
prevent an exported zpool from being imported. Has anyone tested this
recently?
--
Dave
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