[OpenIndiana-discuss] in desperate need of fsck.zfs

[Ray Arachelian]

On 07/24/2012 02:41 PM, Jim Klimov wrote:
>
> Did you try to "zpool import -o readonly=on" and using TXG rollback?
Can't do that now, the pool is actually imported, and it won't let me
export it, nor offline it.

> If your drives wrote crap during disconnection, it is possible that
> some previous ZFS transaction is (more or less) consistent on-disk
> and was not overwritten.

I suspect this might be the case, as the weird behavior survived a few
reboots.  It's as if it's imported half way and then some flag gets set
saying it's not safe to touch the zpool, so everything fails after that
with an I/O error - but at the low level, I can access it just fine via
dd, and to some extend the zdb command.  (Although zdb core dumps with
out of memory.  Not sure if it's because of the bad metadata, or if the
the box is too low on RAM.)

>
> You might want to back up ZFS labels of each disk somewhere, because
> a rollback import clears knowledge of TXGs past some number (i.e.
> CurrentTXG-10); it is possible you'd want to recover that label and
> try a different offset into the past.

I've found something interesting here: 
http://sigtar.com/2009/10/19/opensolaris-zfs-recovery-after-kernel-panic/
I plan on booting off the live ISO off another machine that has more
memory, and attempting it when I get home.  (I can remotely access the
machine, but there's no ILO, so can't force a power off, insert a boot
DVD, etc.)

How do I backup/restore zfs labels?