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List:       freebsd-fs
Subject:    Re: ZFS pool export question
From:       Alan Somers <asomers () freebsd ! org>
Date:       2021-07-20 0:06:10
Message-ID: CAOtMX2g0JdL7GFTOAfsk0XN5SQHjYaTNYL7Oh60vE4JE518MGQ () mail ! gmail ! com
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On Mon, Jul 19, 2021 at 5:58 PM joe mcguckin <joe@via.net> wrote:

> I want to have a disk that I can transfer files between ZFS systems. I
> created a pool with one disk:
>
> zpool create xfer da9
>
> Ok, everything seems to be ok. This is a drive that had a GPT label and 1
> freebsd-zfs partition labelled with the drives serial number.
>
> I want to remove the drive;
>
> zfs umount /xfer
> zpool export xfer
>
> Now I get error messages about a damaged and possible unrecoveracle GPT
> label.
>
> Am I going about this in the right way? I can't simpply remove the drive
> after unmounting it, then ZFS prints errors about a failed VDEV.
>
> Help obi-wan…
>

When you created the pool, you used the whole disk "da9", not the first
partition "da9p1".  So ZFS overwrote the GPT label.  But GPT keeps a backup
label in a location that ZFS didn't overwrite, which is why you now have a
"damaged" GPT label instead of a "nonexistent" one.  If you really want to
have a GPT-formatted disk, you should destroy your pool, recover the label
with "gpart recover da9", then recreate the pool.  Or, you can just forget
about GPT; you don't need it.  To do that, do "gpart destroy -F da9".  That
might also wipe out one of your ZFS labels; I'm not sure.  But like GPT,
ZFS keeps redundant copies of the label.  Oh, it's also unnecessary to do
"zfs umount" each time.  "zpool export" will do that automatically.
-Alan


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