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From: Doug Rabson <dfr@rabson.org>
To: Gergely CZUCZY <phoemix@harmless.hu>
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Date: Wed, 01 Aug 2007 15:37:54 +0100
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Cc: freebsd-fs@freebsd.org
Subject: Re: ZFS on a shared disk
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On Wed, 2007-08-01 at 14:21 +0200, Gergely CZUCZY wrote:
> Hello
> 
> I've seen many checked ZFS in -CURRENT, and I've got
> a question about ZFS in freebsd. I've never checked
> -CURRENT, just thought of whether ZFS can do this or not.
> 
> Let's assume there's a shared disk on a scsi bus, that's
> attached to two boxes. Can that disk be used simultaneously
> with ZFS on the two boxes at the same time? AFAIK UFS2
> is unable to do this, since it doesn't have any on-disk
> synchronization and similar features, that would enable
> an operation like this.

ZFS does not support this at all. It has safeguards that should prevent
you from using a pool on more than one machine. You can transfer
ownership of the pool back and forth between two machines using 'zpool
export' and 'zpool import'.