On 9/25/11 3:15 PM, Phil Turmel wrote:
On 09/25/2011 03:55 AM, Marcin M. Jessa wrote:
[...]
[5]: http://en.wikipedia.org/wiki/Mdadm#Recovering_from_a_loss_of_raid_superblock
These instructions are horrible! If you make the slightest mistake, your data is completely hosed.
Do you know of a better howto ? I was desperate googling a lot, trying
to run different commands first in order to rebuild my raid array, but
with no luck. The only howto that started resyncing was the wikipedia
one I linked to...
If first asks for your "mdadm -E" reports from the drives, but it has you filter them through a grep that throws away important information. (Did you keep that report?)
No, unfortunately I did not.
Next, it has you wipe the superblocks on the array members, destroying all possibility of future forensics.
Then, it has you re-create the array, but omits "--assume-clean", so the array rebuilds. With the slightest mistake in superblock type, chunk size, layout, alignment, data offset, or device order, the rebuild will trash your data. Default values for some of those have changed in mdadm from version to version, so a naive "--create" command has a good chance of getting something wrong.
I tried to run mdadm --assemble --assume-clean /dev/md0 /dev/sd[f-j]1
but that AFAIR only said that the devices which still were members of
the array and were still working were busy. I always stoped the array
before running it.
There is no mention of attempting "--assemble --force" with your original superblocks, which is the correct first step in this situation. And it nearly always works.
I also tried running - with no luck:
# mdadm --assemble --force --scan /dev/md0
# mdadm --assemble --force /dev/md0 /dev/sde1 /dev/sdf1 /dev/sdg1
/dev/sdi1
# mdadm --assemble --force --run /dev/md0 /dev/sde1 /dev/sdf1
/dev/sdg1 /dev/sdi1
and
# mdadm --assemble /dev/md0 --uuid=9f1b28cb:9efcd750:324cd77a:b318ed33
--force
I'm sorry, Marcin, but you shouldn't expect to get your data back. Per your "mdadm -D" report, the rebuild was already 63% done, so the destruction of your data is certainly complete now.
Oh sh** ! :( Really, there is nothing that can be done? What happened
when I started resyncing? I thought the good, working drives would get
the data syneced with the one of drives which failed (it did not really
fail, it was up after reboot and smartctl --attributes --log=selftest
shows it's healthy).
--
Marcin M. Jessa
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
