Hang when importing pool

[Karli Sjöberg]

31 jul 2012 kl. 16.25 skrev 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.

Can´t with the Core i5. Would have to scramble up a Xeon to push in 32G buffered. Will try leveraging with cache device before trying that.


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

Finding txg´s looks "scary", hadn´t thought about readonly though, thanks.


2.1. if this does not work, try older txg
3. Backup your data.

Oh the irony. Yes, that was actually what I was going to do just after destroying those datasets. Have had the backup server just waiting for them all along:)


4. Recreate the pool (undo old mistakes, use gpt labels and proper alignment)

Yeah, I figure recreating and then recv´ing the datasets back in again.


5. Keep dedup=off if you have only 16 GB RAM.

Never wanted to have it active in the first place, so I agree.


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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Med Vänliga Hälsningar
-------------------------------------------------------------------------------
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>