Dear all,
I've been using RAID5 on my video archival server with 6 x 750GB
drives for a year and it was working just fine. Thanks to Niel Brown
and all the team for great job!
Recently while upgrading server to RAID6 I've created new 5 x 750GB
drives RAID6 array, waited for parity calculation to finish (it took
6-7 hours) and started reshaping from 5 to 8 drives. According to
information on this list 2.6.21 or later kernel is required for RAID6
reshaping so I upgraded kernel from 2.6.20 to 2.6.22 (both are
standard Ubuntu server kernels, from Feisty and Gutsy releases resp.).
I started reshape by
mdadm --add /dev/md1 /dev/sda2 /dev/sdb2 /dev/sdd2
mdadm --grow /dev/md1 -n 8
It went through critical section just fine and have been happily
reshaping for few hours. Estimated completion time according to /proc/
mdstat was around 1600-1700 minutes.
Then due to other circumstances I had to reboot my server.
Reboot was going not smoothly (had to reboot few times due to some
errors in my startup scripts - not connected to md in any way I think).
After I rebooted, I could see that md1 array was not stared
automatically and when I'm trying to run
mdadm --assemble /dev/md1
it says "Failed to restore critical section for reshape, sorry."
although it is not the case as far as I can tell (reshaping was going
for at least one or two hours before first reboot).
Please advise me how should I proceed to resolve this situation and
save my data if possible (yes, unfortunately I was going to make
backups in a week but did not had them yet - too bad for me :-( ).
Superblocks on all partitions are fine, mdadm --examine gives the
same information for all 8 partitions, e.g.
/dev/sda2:
Magic : a92b4efc
Version : 00.91.00
UUID : 37d56bd1:4f8ccf24:2421b4fc:05cfad50 (local to
host videoserver)
Creation Time : Mon Sep 3 16:27:04 2007
Raid Level : raid6
Used Dev Size : 730619904 (696.77 GiB 748.15 GB)
Array Size : 4383719424 (4180.64 GiB 4488.93 GB)
Raid Devices : 8
Total Devices : 8
Preferred Minor : 1
Reshape pos'n : 140169216 (133.68 GiB 143.53 GB)
Delta Devices : 3 (5->8)
Update Time : Wed Sep 5 00:15:40 2007
State : clean
Active Devices : 8
Working Devices : 8
Failed Devices : 0
Spare Devices : 0
Checksum : 249b218d - correct
Events : 0.15268
Chunk Size : 1024K
Number Major Minor RaidDevice State
this 5 8 98 5 active sync /dev/sdg2
0 0 8 2 0 active sync /dev/sda2
1 1 8 34 1 active sync /dev/sdc2
2 2 8 50 2 active sync /dev/sdd2
3 3 8 66 3 active sync /dev/sde2
4 4 8 82 4 active sync /dev/sdf2
5 5 8 98 5 active sync /dev/sdg2
6 6 8 114 6 active sync /dev/sdh2
7 7 8 18 7 active sync /dev/sdb2
relevant lines from /etc/mdadm/mdadm.conf:
DEVICE /dev/sd[a-z]*
ARRAY /dev/md1 level=raid6 num-devices=8
UUID=37d56bd1:4f8ccf24:2421b4fc:05cfad50
Kernel version:
root@videoserver:/# uname -a
Linux videoserver 2.6.22-10-server #1 SMP Wed Aug 22 08:06:27 GMT
2007 x86_64 GNU/Linux
mdadm version:
root@videoserver:/# mdadm --version
mdadm - v2.6.3 - 20th August 2007
I had some programming experience before (in userspace only) so I
could try to do some debugging in gdb if necessary - but please
advise me what to look for.
Thank you in advance for any advice and/or help.
Best regards,
Anton Voloshin
Saint Petersburg, Russia
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