Hang when importing pool

[Frank Bartels]

Hi,

I had a very similar problem three times before. The last time I
was able to find a working solution:

0. Add more RAM.
1. Use zdb -h -e pool and find out the *last* good looking txg
   before the current txg.
2. zpool import -T txg -R /pool -o readonly=on pool
2.1. if this does not work, try older txg
3. Backup your data.
4. Recreate the pool (undo old mistakes, use gpt labels and proper alignment)
5. Keep dedup=off if you have only 16 GB RAM.
6. Restore your data.

This is a very short description, but I think you get the idea.

Hope this helps,
Knarf

On Tue, Jul 31, 2012 at 08:31:07 +0200, Karli Sjöberg wrote:
> Hi,
> 
> I?m really struggling with this. I have had a pool with imported filesystems from a Solaris system that had dedup activated. Then, when the time came to erase them, it just stalled. When rebooting, it stalled again at mounting filesystems, and since then, I?ve installed two USB drives to act as root pool with FreeBSD-9.0-RELEASE so that I could import the original pool in recovery, but it always stalls after a couple of hours. Looking at top, I could see that the 16GB RAM was maxed out, so I have heavily tuned down kmem, arc, etc:
> 
> vm.kmem_size_max="512M"
> vm.kmem_size="384M"
> vfs.zfs.arc_max="256M"
> 
> And then I tried importing again, but with the same result; RAM reaches 16G Wired, 0B Free and some swap allocated as well, and then it stalls. So I tried updating, so currently it?s at FreeBSD 9.1-BETA1 #0: Fri Jul 13 22:36:05 CEST 2012, but still no go, it still stalls when I try importing, even like:
> 
> # zpool import -f -F -m pool1
> 
> In the link is a screenshot of CTRL+T after it stalled the last time.
> http://i46.tinypic.com/jhdgrq.png
> 
> There is about 4TB in there that I really need. Please help, I?m out of ideas, and stupid enough not to have gotten it backed up yet.
> 
> 
> Best Regards
> -------------------------------------------------------------------------------
> Karli Sjöberg
> Swedish University of Agricultural Sciences
> Box 7079 (Visiting Address Kronåsvägen 8)
> S-750 07 Uppsala, Sweden
> Phone:  +46-(0)18-67 15 66
> karli.sjoberg at slu.se<mailto:karli.sjoberg at adm.slu.se>
> 
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