zpool detach pool device

[Matthew Seaman]

On 24/01/2012 14:01, Johann Hugo wrote:
> Is there any way to recover data from a (good) disk that was detached from a 
> zpool ?

Possibly, but not necessarily easily.  It depends on how much of your
pool that disk represents.  If it's one half of a mirror, then sure --
easy.  You just need a system you can import the pool too.  The zpool
will show up as degraded, but if you have enough copies of everything it
should still show up.

If it's part of a raidz{,2,3} or your zpool extended over several vdevs,
then you won't be able to recover the entire pool.  Also, you won't be
able to access the data through the filesystem in the usual way.  You'ld
have to read the individual 128k blocks used by ZFS and try and piece
them back into complete files.  Depending on the history of the drive
you might be able to recover a previous version of a file, even if you
can't get the latest one back.  To do this may well require the services
of a specialised data recovery company.

If you're worried about leaking confidential information on old disk
drives, then a few passes with dban should render the data unrecoverable
except by heroic measures.  Unless you're dealing in highly sensitive
material, that is generally sufficient.

	Cheers,

	Matthew

-- 
Dr Matthew J Seaman MA, D.Phil.                   7 Priory Courtyard
                                                  Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey     Ramsgate
JID: matthew at infracaninophile.co.uk               Kent, CT11 9PW

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