Getting ZFS pools back.

Willem Jan Withagen wjw at
Sun Apr 29 17:27:22 UTC 2018

On 29-4-2018 16:40, Alan Somers wrote:
> So your kernel couldn't find the pool.  That might be due to a GEOM 
> module that wasn't loaded but should've been (were you using gmirror or 
> geli or something?).  Or you might've accidentally destroyed the pool.  
> It would still show up in "zdb -l", albeit in the destroyed state.  Or 
> you might've accidentally destroyed the partition.  If the pool had 
> resided on the disk's last partition, then "zdb -l /dev/ada0" still 
> would've seen the label, since there's a copy of the label at the end of 
> the device.  But if you've reused the disk, then there's no way to know 
> for sure.

Hi Alan,

I still have one of the original disks of the mirror, but the 
system/hardware causing trouble is back in use in the DC.
No geli, or anything other that basic GEOM was involved.
Disks were running on GPT:

And yes zdb -l was able to find both pools: zroot, and zfsdata.
And I'm pretty sure I did not destroy them on purpose. ;-)

Trouble started when I installed (freebsd-update) 11.1 over a running 
10.4. Which is sort of scarry?

But because the system needed to go back on the air, I did only so much 
to recover the original stuff. But it just kept naging me over the GUID 
it could not find. So for sake of progress I reinstalled the system on 
one of the mirror disks, keeping the other one.

So I could hook that disk up to my Freetest play box, and see what that 
brings. If anyone is interested.
But than again the zpool import could have fixed what was broken in the 
first place. Haven't looked at it yet, since the 12 hour straight 
session yesterday was enough for the weekend.


> -Alan
> On Sun, Apr 29, 2018 at 8:29 AM, Willem Jan Withagen <wjw at 
> <mailto:wjw at>> wrote:
>     On 28/04/2018 20:43, Richard Yao wrote:
>         What is the output of ‘zpool import‘ with no arguments?
>     If I boot thru aa mem-stick....
>     # zpool import
>     #
>     So, empty line
>     In the mean time I rebuild the system.
>     Was able to retreive the data by a convoluted incantation of
>     'zpool import -fmNF' or something like that.
>     Made a full backup, and started fresh.
>     --WjW
>             On Apr 28, 2018, at 11:42 AM, Willem Jan Withagen
>             <wjw at <mailto:wjw at>> wrote:
>             Hi,
>             I had this server crash on me, and first it just complained
>             about not being able to boot because it could not find the guid.
>             Now I cannot even import the pools any longer.
>             Althoug zdb -l /dev/ada0 still gives me data that indicates
>             that there should be a ZFS pool on that partition.
>             Any suggestions on how to get the pools/data back online?
>             Help would be highly appreciated, since restoring it from
>             backups is going to quite some work.
>             Thanx,
>             --WjW

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