zfs discuss - Jan 2008 - Can''t access my data

Hi Folks..

I have/had a zpool containing one filesystem.

I had to change my hostid and needed to import my pool, (I''ve done his 
OK in the past).
After the import the mount of my filesystem failed.

# zpool import homespool
cannot mount ''homespool/homes'': mountpoint or dataset is busy

The data seems it might still exist, (correct amount of used space is 
reported), but /homespool
doesn''t provide me any obvious way to get to it any more.

# zfs list
NAME              USED  AVAIL  REFER  MOUNTPOINT
homespool        9.91G   124G    18K  /homespool
homespool/homes  9.91G   124G  9.91G  /homes

ls -laR  /homespool
/homespool:
total 5
drwxr-xr-x   2 root     sys            2 Jan  4 11:48 .
drwxr-xr-x  48 root     root        1024 Jan  4 20:45 ..

I''d dearly love to recover this pool, (no backup, yes I know :-(.
It WAS a mirror, I scrubbed it and no errors were seen, I''ve since
detached
one device to try to see if anything changed.

Can anyone point out how I might read the data ??

TIA
-George

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On Jan 4, 2008 2:42 PM, George Shepherd - Sun Microsystems Home system
<George.Shepherd at sun.com> wrote:
> Hi Folks..
>
> I have/had a zpool containing one filesystem.
>
> I had to change my hostid and needed to import my pool, (I''ve done
his
> OK in the past).
> After the import the mount of my filesystem failed.
>
> # zpool import homespool
> cannot mount ''homespool/homes'': mountpoint or dataset is
busy
                                  ^^^^^^^^^^
> # zfs list
> NAME              USED  AVAIL  REFER  MOUNTPOINT
> homespool        9.91G   124G    18K  /homespool
> homespool/homes  9.91G   124G  9.91G  /homes
                                        ^^^^^^
Is something else already mounted at /homes?

# df -k /homes

Did you or someone else "cd /homes" before trying this, thus
causing the mount point to be busy?

# fuser /homes

If you still can''t resolve it

# zfs set mountpoint=/somewhere_else homespool/homes
# zfs mount -a     (not sure this needed)
# cd /somewhere_else

-- 
Mike Gerdts
http://mgerdts.blogspot.com/

Heya,
> I have/had a zpool containing one filesystem.
Cool, simple scenario.
> I had to change my hostid and needed to import my pool, (I''ve done
his
> OK in the past).
> After the import the mount of my filesystem failed.
I take it you did the ''export'' part with the other hostid?
Wondering if
something could have got ''kludged'' prior to the host change.
> # zpool import homespool
> cannot mount ''homespool/homes'': mountpoint or dataset is
busy
What is the path it''s being mounted on? Does it exist, is there nothing
on it etc?

If all else fails you could try a forced unmount with zfs unmount -f
homespool/homes . The ZFS developers on this list might cringe at that
suggestion though. :)
> The data seems it might still exist, (correct amount of used space is
> reported), but /homespool
> doesn''t provide me any obvious way to get to it any more.
> # zfs list
> NAME              USED  AVAIL  REFER  MOUNTPOINT
> homespool        9.91G   124G    18K  /homespool
> homespool/homes  9.91G   124G  9.91G  /homes
> 
> ls -laR  /homespool
<snip>

What about ls /homes ? That''s the specified mount point and by the
looks
of the above message the mount hasn''t succeeded.

When a zfs filesystem has a specified mountpoint outside of the volumes
base mount I believe (and there''s people on this list who could
probably
confirm) it disappears from the volume mount. It may add a symlink too
(I''m just not sure if that''s automatic :)) but since the mount
failed it
doesn''t make sense.
> I''d dearly love to recover this pool, (no backup, yes I know :-(.
> It WAS a mirror, I scrubbed it and no errors were seen, I''ve since
detached
> one device to try to see if anything changed.
Well, the good things is you''ve got the volume mounted. Assuming zpool
status homespool returns a good result you should be in luck.

Hope that helps,

-- 
Stuart Low
Systems Infrastructure Manager
iseek Communications Pty Ltd
Excellence in business data solutions
ph 1300 661 668 fax 1300 661 540
www.iseek.com.au

I seem to remember hostid being added to the zpool to solve a bug for the poor
man''s storage cluster.

Trying doing a zdb -v ( you should see 4 copies and note if hostid is a field
and if it differs from the current one)

you can also try a  zpool import -f -a

I''ve seen cases where zfs mount -v -a fail but a zpool import -f -a
works.  I don''t yet know why but I know zpool import searches /dev/dsk/
trees and my hunch is that zfs mount looks for a hostid match.
 
 
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