Attempting to recover from a downed RAID5 array:
# mdadm -S /dev/md0
# mdadm -Af /dev/md0 /dev/hdm4 /dev/hde2 /dev/hdo2 /dev/hdh2 /dev/hdf2 /dev/hdg2
Segmentation fault
#
Could it be that my mdadm is making some assumptions about my system
that it shouldn't? This mdadm was compiled on a different 2.6.8
system, since my RAID5 box can't access its compiler, which is on the
RAID5 partition. Is there anyone out there who has a mdadm static
binary that is compiled for kernel 2.6.8-gentoo-r3?
Here are more details:
I have a gentoo system (kernel 2.6.8-gentoo-r3) with a 7 drive RAID5
array. Recently that array went down, and I was advised by the list
to try mdadm.
When I boot, I see the "Starting up RAID devices: ... * Trying
md0... [ !!FAILED ]" and the system drops me to the shell. I type:
# cat /proc/mdstat
Personalities : [raid1] [raid5]
md0 : inactive hdm4[0] hde2[6] hdo2[5] hdh2[4] hdf2[3] hdg2[2]
1464789888 blocks
unused devices: <none>
OK, the array is missing partition hdp2. dmesg says it has an invalid
superblock:
# dmesg | grep hdp
ide7: BM-DMA at 0xd808-0xd80f, BIOS settings: hdo:DMA, hdp:DMA
hdp: WDC WD2500JB-00GVA0, ATA DISK drive
hdp: max request size: 1024KiB
hdp: 488397168 sectors (250059 MB) w/8192KiB Cache, CHS=30401/255/63, UDMA (100)
md: invalid raid superblock magic on hdp2
md: hdp2 has invalid sb, not importing!
Adding 64220k swap on /dev/hdp1. Priority:-2 extents:1
I didn't see any indication that there is anything wrong with the hdp
drive. Here is my /etc/mdadm.conf file:
# cat /etc/mdadm.conf
DEVICE partitions
ARRAY /dev/md0 level=raid5 num-devices=7 UUID=d312c423:e2eeeff5:3401806f:ab10e3c
devices=/dev/ide/host2/bus0/target0/lun0/part2,/dev/ide/host2/bus0/target1/lun0/part2,/dev/ide/host2/bus1/target0/lun0/part2,/dev/ide/host2/bus1/target1/lun0/part2,/dev/ide/host6/bus0/target0/lun0/part4,/dev/ide/host6/bus1/target0/lun0/part2
Since /proc/mdstat reports that six of the seven drives are already
assembled, I tried running as-is:
# mdadm --run /dev/md0
mdadm: failed to run array /dev/md0: Invalid argument
# mdadm -v --run --force /dev/md0
mdadm: failed to run array /dev/md0: Invalid argument
Hmm... not very descriptive. I looked at the end of dmesg again for
more hints:
# dmesg | tail -18
md: pers->run() failed ...
raid5: device hdm4 operational as raid disk 0
raid5: device hde2 operational as raid disk 6
raid5: device hdo2 operational as raid disk 5
raid5: device hdh2 operational as raid disk 4
raid5: device hdf2 operational as raid disk 3
raid5: device hdg2 operational as raid disk 2
raid5: cannot start dirty degraded array for md0
RAID5 conf printout:
--- rd:7 wd:6 fd:1
disk 0, o:1, dev:hdm4
disk 2, o:1, dev:hdg2
disk 3, o:1, dev:hdf2
disk 4, o:1, dev:hdh2
disk 5, o:1, dev:hdo2
disk 6, o:1, dev:hde2
raid5: failed to run raid set md0
md: pers->run() failed ...
It is at this point that I tried stopping and starting the array as
described on the mailing list:
# mdadm -S /dev/md0
# mdadm -Af /dev/md0 /dev/hdm4 /dev/hde2 /dev/hdo2 /dev/hdh2 /dev/hdf2 /dev/hdg2
Segmentation fault
#
Any suggestions?
Thanks,
Dave
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