Help Recovering FBSD 8 ZFS System

Daniel Staal DStaal at
Mon Jan 2 20:36:56 UTC 2012

--As of December 31, 2011 1:40:59 PM -0800, Drew Tomlinson is alleged to 
have said:

> Thus it appears I am missing ad16 that I used to have.  My data zpool was
> the bulk of my system with over 600 gig of files and things I'd like to
> have back.  I thought that by creating a raidz1 I could avoid having to
> back up the huge drive and avoid this grief.  However it appears I have
> lost 2 disks at the same time.  :(
> Any thoughts before I just give up on recovering my data pool?

Ouch.  All I can really say is 'Redundancy is not backup', but that's a bit 

The one thing you haven't mentioned trying that might be worth the attempt 
is trying the recovery from a 9.0 disk.  There has been work done on the 
ZFS system, and it's possible that something might work.   But that's 
mostly just to be thorough...

As for what it was telling you: It was just saying it couldn't open the 
drives.  ;)  Which does bring up one other option: If you've got a 
different drive controller, you might try plugging the drives into it.  (In 
the hopes that it's the *controller* and not the drive that's gone bad. 
Unlikely, bit it *does* happen.)

(Depending on the value of the data pool, a good data recovery service 
might be able to do something as well.  But they'd have to be a very good 
service, and know what they were working with.)

> And regarding my root pool, my system can't mount root and start.  What
> do I need to do to boot from my degraded root pool.  Here's the current
> status:
># zpool status
>    pool: root
>   state: DEGRADED
> status: One or more devices could not be opened.  Sufficient replicas
> exist for
>          the pool to continue functioning in a degraded state.
> action: Attach the missing device and online it using 'zpool online'.
>     see:
>   scrub: none requested
> config:
>          NAME                                            STATE     READ
>          root                                            DEGRADED     0
> 0     0
>            mirror                                        DEGRADED     0
> 0     0
>              gptid/5b623854-6c46-11de-ae82-001b21361de7  ONLINE       0
> 0     0
>              12032653780322685599                        UNAVAIL      0
> 0     0  was /dev/ad6p3
> Do I just need to do a 'zpool detach root /dev/ad6p3' to remove it from
> the pool and get it to boot?  And then once I replace the disk a 'zpool
> attach root <new partition>' to fix?
> Thanks for your time.

Personally, I'd do a 'zpool replace /dev/ad6p3 /dev/$NEWDRIVE', but the 
above should work as well.  What's odd though is that you can't boot from 
it as is: Degraded should be considered functional, and it should let you 
boot.  You mentioned updating the zpool to v15.  Did you update the boot 
block at the same time?  (Just checking the basics.)  It'd need to be able 
to read the updated zpool.

Daniel T. Staal

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