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From: Daniel Hagerty <hag@linnaean.org>
To: Ulrich =?utf-8?Q?Sp=C3=B6rlein?= <uqs@FreeBSD.org>
Subject: Re: Zpool surgery
References: <20130127103612.GB38645@acme.spoerlein.net>
 <1F0546C4D94D4CCE9F6BB4C8FA19FFF2@multiplay.co.uk>
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Sender: Daniel Hagerty <hag@perdition.linnaean.org>
Date: Mon, 28 Jan 2013 13:06:10 -0500
In-Reply-To: <20130128085820.GR35868@acme.spoerlein.net> (Ulrich Sp's message
 of "Mon, 28 Jan 2013 09:58:20 +0100")
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Ulrich Sp=C3=B6rlein <uqs@FreeBSD.org> writes:

> But are you then also supposed to be able send incremental snapshots to
> a third pool from the pool that you just cloned?

    I can't speak to your problems, but I did recently do what you seem
to be doing, without incident.  That is, I had a pool and an archive.  I
copied datasets from pool to a new pool', and pool' could send to the
archive as if it were the original pool.

    Two possible differences in what I do that leap to mind:

1. I only send select snapshots to archive; the synchronization
snapshots are not among them.
2. I use receive -F.

> How does the receiving pool known that it has the correct snapshot to
> store an incremental one anyway? Is there a toplevel checksum, like for
> git commits? How can I display and compare that?

    I don't know for sure, but I'd hazard a guess that:

$ zfs get -p guid pool/home@daily-2013-01-28
NAME                        PROPERTY  VALUE  SOURCE
pool/home@daily-2013-01-28  guid      259258190084829958  -

    plays a part.

    Good luck!