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Re: [zfs-discuss] Re: ZFS - SAN and Raid

Subject: Re: [zfs-discuss] Re: ZFS - SAN and Raid
From: Richard Elling
Date: Tue, 19 Jun 2007 10:26:32 -0700
Victor Engle wrote:
Roshan,

As far as I know, there is no problem at all with using SAN storage
with ZFS and it does look like you were having an underlying problem
with either powerpath or the array.

Correct.  A write failed.

The best practices guide on opensolaris does recommend replicated
pools even if your backend storage is redundant. There are at least 2
good reasons for that. ZFS needs a replica for the self healing
feature to work. Also there is no fsck like tool for ZFS so it is a
good idea to make sure self healing can work.

Yes, currently ZFS on Solaris will panic if a non-redundant write fails.
This is known and being worked on, but there really isn't a good solution
if a write fails, unless you have some ZFS-level redundancy.

NB. fsck is not needed for ZFS because the on-disk format is always
consistent.  This is orthogonal to hardware faults.

I think first I would track down the cause of the messages just prior
to the zfs write error because even with replicated pools if several
devices error at once then the pool could be lost.

Yes, multiple failures can cause data loss.  No magic here.
 -- richard
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