[zfs-discuss] cannot import 'home': I/O error Destroy and re-create the pool from a backup source

Anton Gubar'kov anton.gubarkov at iits.ru
Thu Apr 26 16:01:05 EDT 2018

Dear friends,
I used zdb -d to display data about the snapshots I have in the pool's
datasets. I checked the txg numbers of the snapshots in the dataset I'm
most anxious to recover and started my import attempts from the most recent
working through to the past. The 3rd one proved to be working. I has to
restart my host after every unsuccessful attempt due to zfs freeze.

The copy still runs and will do for at least 6 more hours.
The current zpool stat -v looks like:
  pool: home
 state: ONLINE
status: One or more devices has experienced an error resulting in data
        corruption.  Applications may be affected.
action: Restore the file in question if possible.  Otherwise restore the
        entire pool from backup.
   see: http://zfsonlinux.org/msg/ZFS-8000-8A
  scan: scrub repaired 0B in 0 days 09:58:16 with 0 errors on Wed Mar 14
09:21:55 2018

        NAME                            STATE     READ WRITE CKSUM
        home                            ONLINE       0     0   122
          raidz2-0                      ONLINE       0     0   514
            wwn-0x5000c500a41a0a00      ONLINE       0     0     0
            wwn-0x5000c500a41ae340      ONLINE       0     0     0
            wwn-0x5000c500a41b4c57      ONLINE       0     0     7
            wwn-0x5000c500a41b7572      ONLINE       0     0     0
            wwn-0x5000c500a41ba99c      ONLINE       0     0     0
            wwn-0x5000c500a41babe8      ONLINE       0     0     8
          wwn-0x30000d1700d9d40f-part2  ONLINE       0     0     0

errors: Permanent errors have been detected in the following files:


I don't really care about home/users/anrdey dataset where permanent errors
are reported. I don't understand the errors stats. What do checksum errors
on pool and raidz2-0 vdev level mean? They keep growing while device-level
checksum errors stay.
There was no read error reported so far to the copying process (around 1TB
of data is copied already). There are no messages in zfs debug log since
the import had been completed.


On Thu, Apr 26, 2018 at 6:23 PM Raghuram Devarakonda via zfs-discuss <
zfs-discuss at list.zfsonlinux.org> wrote:

> On Thu, Apr 26, 2018 at 11:12 AM, Anton Gubar'kov via zfs-discuss
> <zfs-discuss at list.zfsonlinux.org> wrote:
> > Chris, thank you very much for the hint! After a couple of panics, I
> could
> > find the intact txg and import the pool rewinding it to one of the
> > snapshots' txg. I'm copying the contents now. I understand that I may
> not be
> > able to copy everything, but this is better than loosing everything.
> That's great. Can you please describe how you figured out the valid txg?
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at list.zfsonlinux.org
> http://list.zfsonlinux.org/cgi-bin/mailman/listinfo/zfs-discuss
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