zfs discuss - Jan 2010 - Can''t export pool after zfs receive

I initialized a new whole-disk pool on an external USB drive, and then did
zfs send from my big data pool and zfs recv onto the new external pool. 
Sometimes this fails, but this time it completed.  Zpool status showed no
errors on the external pool.

Zpool export hangs, with  no apparent disk activity.

The processes involved can''t be killed even with kill -9, either.

I''m seriously considering unplugging the external drive, rebooting the
system, and seeing what I''ve got.  Any other ideas?

Any idea why this kind of thing happens so often?

-- 
David Dyer-Bennet, dd-b at dd-b.net; dd-b.net
Snapshots: dd-b.net/dd-b/SnapshotAlbum/data
Photos: dd-b.net/photography/gallery
Dragaera: dragaera.info

On Jan 4, 2010, at 10:26 AM, David Dyer-Bennet wrote:
> I initialized a new whole-disk pool on an external USB drive, and  
> then did
> zfs send from my big data pool and zfs recv onto the new external  
> pool.
> Sometimes this fails, but this time it completed.  Zpool status  
> showed no
> errors on the external pool.
>
> Zpool export hangs, with  no apparent disk activity.
>
> The processes involved can''t be killed even with kill -9, either.
This occurs when threads are asleep, waiting on an I/O to complete.
Signals are not delivered until the thread awakes -- when the I/O
completes.

Check iostat to see if an I/O is stuck in the actv queue.
> I''m seriously considering unplugging the external drive, rebooting
the
> system, and seeing what I''ve got.  Any other ideas?
>
> Any idea why this kind of thing happens so often?
Crappy hardware? :-)
  -- richard

> I initialized a new whole-disk pool on an external
> USB drive, and then did zfs send from my big data pool and zfs recv onto
the
> new external pool. 
> Sometimes this fails, but this time it completed.
That''s the key bit for me - zfs send /receive should not just fail at
random.  It sounds like your problem is not just that you can''t export
the pool.

As Richard says, that sounds like bad hardware / drivers.  Something is causing
problems for ZFS.
-- 
This message posted from opensolaris.org

On Mon, January 4, 2010 13:51, Ross wrote:
>> I initialized a new whole-disk pool on an external
>> USB drive, and then did zfs send from my big data pool and zfs recv
onto
>> the
>> new external pool.
>> Sometimes this fails, but this time it completed.
>
> That''s the key bit for me - zfs send /receive should not just fail
at
> random.  It sounds like your problem is not just that you can''t
export the
> pool.
It''s equally flaky in virtual environments, in my experience.  Sadly. 
Send / receive seems to not be ready for prime time yet.  (I had to give
up on incremental completely, since that was erroring out.)
> As Richard says, that sounds like bad hardware / drivers.  Something is
> causing problems for ZFS.
Always possible.  I paid twice or so what I usually pay for systems to buy
this one, including ECC memory and such, but none of that is any guaranty
I got it right.  Frustrating, though.

-- 
David Dyer-Bennet, dd-b at dd-b.net; dd-b.net
Snapshots: dd-b.net/dd-b/SnapshotAlbum/data
Photos: dd-b.net/photography/gallery
Dragaera: dragaera.info