The RAID device appears to be inactive somehow:
# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5]
[raid4] [raid10]
md_d0 : inactive sda4[0](S)
241095104 blocks
# mdadm --detail /dev/md0
mdadm: md device /dev/md0 does not appear to be active.
Code:
matt@OptimusPrime:~$ sudo mdadm --detail /dev/md0
mdadm: md device /dev/md0 does not appear to be active.
matt@OptimusPrime:~$ sudo mdadm --run /dev/md0
mdadm: failed to run array /dev/md0: Input/output error
matt@OptimusPrime:~$ sudo mdadm --detail /dev/md0
/dev/md0:
Version : 00.90
Creation Time : Thu Nov 24 18:01:12 2011
Raid Level : raid5
Used Dev Size : 1953511936 (1863.01 GiB 2000.40 GB)
Raid Devices : 4
Total Devices : 2
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Mon Jan 21 16:40:08 2013
State : active, degraded, Not Started
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 64K
UUID : dc256ec9:45cdecc4:fbf2ea5a:12bfd232 (local to host OptimusPrime)
Events : 0.90803
Number Major Minor RaidDevice State
0 0 0 0 removed
1 8 33 1 active sync /dev/sdc1
2 8 17 2 active sync /dev/sdb1
3 0 0 3 removed
matt@OptimusPrime:~$
matt@OptimusPrime:~$ sudo mdadm --examine /dev/sd[bcde]1
/dev/sdb1:
Magic : a92b4efc
Version : 00.90.00
UUID : dc256ec9:45cdecc4:fbf2ea5a:12bfd232 (local to host OptimusPrime)
Creation Time : Thu Nov 24 18:01:12 2011
Raid Level : raid5
Used Dev Size : 1953511936 (1863.01 GiB 2000.40 GB)
Array Size : 5860535808 (5589.04 GiB 6001.19 GB)
Raid Devices : 4
Total Devices : 2
Preferred Minor : 0
Update Time : Mon Jan 21 16:40:08 2013
State : active
Active Devices : 2
Working Devices : 2
Failed Devices : 1
Spare Devices : 0
Checksum : ee0ec535 - correct
Events : 90803
Layout : left-symmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
this 2 8 17 2 active sync /dev/sdb1
0 0 0 0 0 removed
1 1 8 33 1 active sync /dev/sdc1
2 2 8 17 2 active sync /dev/sdb1
3 3 0 0 3 faulty removed
/dev/sdc1:
Magic : a92b4efc
Version : 00.90.00
UUID : dc256ec9:45cdecc4:fbf2ea5a:12bfd232 (local to host OptimusPrime)
Creation Time : Thu Nov 24 18:01:12 2011
Raid Level : raid5
Used Dev Size : 1953511936 (1863.01 GiB 2000.40 GB)
Array Size : 5860535808 (5589.04 GiB 6001.19 GB)
Raid Devices : 4
Total Devices : 2
Preferred Minor : 0
Update Time : Mon Jan 21 16:40:08 2013
State : active
Active Devices : 2
Working Devices : 2
Failed Devices : 1
Spare Devices : 0
Checksum : ee0ec543 - correct
Events : 90803
Layout : left-symmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
this 1 8 33 1 active sync /dev/sdc1
0 0 0 0 0 removed
1 1 8 33 1 active sync /dev/sdc1
2 2 8 17 2 active sync /dev/sdb1
3 3 0 0 3 faulty removed
mdadm: No md superblock detected on /dev/sdd1.
/dev/sde1:
Magic : a92b4efc
Version : 00.90.00
UUID : dc256ec9:45cdecc4:fbf2ea5a:12bfd232 (local to host OptimusPrime)
Creation Time : Thu Nov 24 18:01:12 2011
Raid Level : raid5
Used Dev Size : 1953511936 (1863.01 GiB 2000.40 GB)
Array Size : 5860535808 (5589.04 GiB 6001.19 GB)
Raid Devices : 4
Total Devices : 3
Preferred Minor : 0
Update Time : Mon Jan 21 16:10:12 2013
State : clean
Active Devices : 2
Working Devices : 3
Failed Devices : 1
Spare Devices : 1
Checksum : ee102159 - correct
Events : 90796
Layout : left-symmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
this 4 8 65 4 spare /dev/sde1
0 0 0 0 0 removed
1 1 8 33 1 active sync /dev/sdc1
2 2 8 17 2 active sync /dev/sdb1
3 3 0 0 3 faulty removed
4 4 8 65 4 spare /dev/sde1
matt@OptimusPrime:~$
Code:
sudo -i
mdadm --stop /dev/md0
mdadm --assemble --force /dev/md0 /dev/sd[bce]1