Hi all,
Ok, this might be to stir some things up again but I would like to
make this more clear.
I have been reading this and other threads regarding ZFS on SAN and
how well ZFS can recover from a serious error such as a cached disk
array goes down or the connection to the SAN is lost. What I am
hearing (Miles, ZFS-8000-72) is that sometimes you can end up in an
unrecoverable state that forces you to restore the whole pool. I have
been operating quite large deployments of SVM/UFS VxFS/VxVM for some
years and while you sometimes are forced to do a filesystem check and
some files might end up in lost+found I have never lost a whole
filesystem. This is despite whole arrays crashing, split-brain
scenarios etc. In the previous discussion a lot of fingers was pointed
at hardware and USB connections, but then some people mentioned
loosing pools located SAN in this thread.
We are currently evaluating if we should begin to implement ZFS in our
SAN. I can see great opportunities with ZFS but if we have a higher
risk of loosing entire pools that is a serious issue. I am aware that
the other filesystems might not be in a correct state after a serious
failure, but as stated before that can be much better than restoring
a multi terabyte filesystem from yesterdays backup.
So, what is the opinion, is this an existing problem even when using
enterprise arrays? If I understand this correctly there should be no
risk of loosing an entire pool if DKIOCFLUSHWRITECACHE is honored by
the array?
If it is a problem, will the worst case scenario be at least on pair
with UFS/VxFS when 6667683 is fixed?
Grateful for any additional information.
Regards
Henrik Johansson
http://sparcv9.blogspot.com
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