ZFS Snapshot problems

[Matthew Seaman]

On 12/02/2012 13:10, Peter Maloney wrote:
> I don't know what side effects that change has though. You can usually
> assume that ZFS will just figure out the pool regardless of labels
> (because it uses its own label metadata; see zdb output to see the other
> id), but apparently your case is something special, getting actual
> errors instead of only wrong names.

Yes.  This is most perplexing -- it's such a specific effect.  The gpt
thing may well be a red herring.  It is odd though that zdb somehow
discovers the gpart labels through reading zpool.cache, but zpool(1)
uses the gptids instead.

> In my experience, there are no strange side effects. But maybe there
> would be if you inserted some other disks with the same gpt/ labels.

That's not going to be a problem in my environment.  It's not physically
possible to insert more disks[*], and I'd have to power off to swap out
one of the existing ones.

> And another long shot idea: you could also try booting off of a DVD and
> importing using "-o cachefile=.... -o altroot=..." and then copying the
> cachefile over your current one (/boot/zfs/zpool.cache I think) to see
> if it then has the right names when you reboot again.
> 
> 
> And again, I don't know if your data is at risk using any of my
> suggestions. I always play around with things like that in test virtual
> machines first.

Hmmm... as the one and only operational effect of this problem I've
identified is to prevent my getting good backups, that's quite the
catch-22 there.

Definitely time to go virtual, lest the cure have worse effects than the
disease.

	Thanks,

	Matthew

[*] Well, unless I created a zfs on a usb stick, but I've no reason to
do that.

-- 
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

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 267 bytes
Desc: OpenPGP digital signature
Url : http://lists.freebsd.org/pipermail/freebsd-fs/attachments/20120212/29513537/signature.pgp