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Subject: Re: Advice on disk media error recovery
From: John Nielsen <lists@jnielsen.net>
In-Reply-To: <uh7lhkcfce0.fsf@P142s.sics.se>
Date: Thu, 5 Feb 2015 12:12:22 -0700
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To: Bengt Ahlgren <bengta@sics.se>
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On Feb 5, 2015, at 11:20 AM, Bengt Ahlgren <bengta@sics.se> wrote:

> I have a five-disk non-redundant zpool where two disks have media
> errors.  One with five sectors unreadable and the other with three
> sectors.
>=20
> I would like to recover as much data as possible from these disks.  =
What
> are my possible options?  (And, no, there is no backup.)

(Aside from learn to always have backups and where feasible to use =
redundant disks...)

> Copying the files that can be read from the pool to a different pool =
on
> other disks?

That would be a good place to start so you at least have backups of most =
things. You could use rsync but you would lose and ZFS dataset structure =
and attributes.

You could add disks to the system and do "zpool replace".

You could make a new (hopefully redundant) pool and try "zpool send | =
zpool recv". I don't know firsthand if that would cope with errors.

> Making block-copy clones of the faulty disks and removing files that =
had
> the media errors?

This might be a last resort. You should export the zpool before you =
start.