Kernel: 2.6.24 i386
mdadm: 2.6.4
Hi,
I had a RAID5 array in the configuration 250/250/400/400 (so only
250/250/250/250 was actually being used)
After a partition rearrangement it was possible to increase the size
of the two 250 partitions to 400. I did the following:
mdadm --fail partition
mdadm --remove partition
cfdisk resize partition
mdadm --add partition
wait some hours for rebuild to complete
Twice, once for each 250G partition.
The new array was running fine. Here is its status:
champagne:/home/jules# mdadm --detail /dev/md0
/dev/md0:
Version : 00.90.03
Creation Time : Tue Jan 30 21:28:07 2007
Raid Level : raid5
Array Size : 726732096 (693.07 GiB 744.17 GB)
Used Dev Size : 242244032 (231.02 GiB 248.06 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Mon Jun 2 22:46:33 2008
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 64K
UUID : 52252ae8:5d1fd858:31a51f4c:5ff55ddd
Events : 0.1638776
Number Major Minor RaidDevice State
0 8 2 0 active sync /dev/sda2
1 8 18 1 active sync /dev/sdb2
2 8 50 2 active sync /dev/sdd2
3 8 34 3 active sync /dev/sdc2
However I was under the impression --grow --size=max would grow it up
to the real limits of the partitions. This didn't work.
Thinking something was cached in internal tables with incorrect
partition sizes, I rebooted the machine.
Bad idea :(
The RAID array failed to reconstruct. The boot messages said there
were only two working devices, not enough to start array.
/dev/sdd2 and /dev/sd2 (which were the partitions I didn't touch) were
both there. /dev/sda2 and /dev/sdb2 didn't add.
I tried (mistake?) adding /dev/sda2 explicitly with --add but it added
as a spare, not as a proper member.
I tried assembling explicitly with --assemble /dev/sda2 /dev/sdb2
/dev/sdc2 /dev/sdd2 and it complained of no RAID superblock on
/dev/sdb2.
Help? What next ;) Is there enough information in /dev/sdd2 and
/dev/sdc2 to reconstruct the apparently missing superblocks on /dev/sda2
and /dev/sdb2? Do I need to try to resize my partitions back to their
old size so it can find the old superblock? Even if by adding /dev/sda2
as a spare I've corrupted its superblock entirely, sdb2 should still
have enough to save my array with 3 out of 4 devices?
Many thanks,
Jules
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