zpool import hangs when out of space - Was: zfs pool import hangs on [tx->tx_sync_done_cv]

[mark]

On 10/13/2014 22:10, Steven Hartland wrote:
> So the issue is simply the pool is out of space to perform the import
> as that process, when not readonly, requires space to write to the pool.
>
> The problem with that is that during this process it has the pool lock so
> any subsequent zpool actions are dead in the water as they will block
> waiting on that lock.
>
> Something to discuss with the openzfs guys, but I would say the import
> should fail with a no space error.
>
> So Mark the mystery is solved, when you upgraded you ran the pool so low
> on space that it now can't be imported RW as that requires a write.
>
>     Regards
>     Steve

Thank you both for analysis and effort!

I can't rule out the possibility that my main system pool
on a SSD was low on space at some point in time, but the
three 4 GiB cloned pools (sys1boot and its brothers) were all
created as a zfs send / receive copies of the main / (root)
file system and I haven't noticed anything unusual during
syncing. This syncing was done manually (using zxfer) and
independently from the upgrade on the system - on a steady/quiet
system, when the source file system definitely had sufficient
free space.

The source file system now shows 1.2 GiB of usage shown
by df:
   shiny/ROOT  61758388  1271620  60486768  2%  /
Seems unlikely that the 1.2 GiB has grown to 4 GiB space
on a cloned filesystem.

Will try to import the main two pools after re-creating
a sane boot pool...

   Mark