helix:~# cat /proc/mdstat Personalities : [raid6] [raid5] [raid4] md1 : active raid5 hdg3[3] hde3[2] hda3[0] 519228480 blocks level 5, 64k chunk, algorithm 2 [4/3] [U_UU] md0 : active raid5 hdg4[3] hde4[2] hda4[0] 7325376 blocks level 5, 64k chunk, algorithm 2 [4/3] [U_UU] unused devices: helix:~# mdadm --examine /dev/hda3 /dev/hda3: Magic : a92b4efc Version : 00.90.00 UUID : f0ed99aa:a959ca9d:6806265f:a9f9a2da Creation Time : Tue May 8 23:07:00 2007 Raid Level : raid5 Device Size : 173076160 (165.06 GiB 177.23 GB) Array Size : 519228480 (495.17 GiB 531.69 GB) Raid Devices : 4 Total Devices : 4 Preferred Minor : 1 Update Time : Tue May 8 23:07:00 2007 State : clean Active Devices : 3 Working Devices : 3 Failed Devices : 1 Spare Devices : 0 Checksum : ec46fdf4 - correct Events : 0.1 Layout : left-symmetric Chunk Size : 64K Number Major Minor RaidDevice State this 0 3 3 0 active sync /dev/hda3 0 0 3 3 0 active sync /dev/hda3 1 1 0 0 1 faulty 2 2 33 3 2 active sync /dev/hde3 3 3 34 3 3 active sync /dev/hdg3 helix:~# mdadm --examine /dev/hda4 /dev/hda4: Magic : a92b4efc Version : 00.90.00 UUID : 4ec47a27:9268fe7d:ee4e9520:8f860d8f Creation Time : Tue May 8 23:04:04 2007 Raid Level : raid5 Device Size : 2441792 (2.33 GiB 2.50 GB) Array Size : 7325376 (6.99 GiB 7.50 GB) Raid Devices : 4 Total Devices : 3 Preferred Minor : 0 Update Time : Tue May 8 23:05:00 2007 State : clean Active Devices : 3 Working Devices : 3 Failed Devices : 1 Spare Devices : 0 Checksum : 94d63e30 - correct Events : 0.4 Layout : left-symmetric Chunk Size : 64K Number Major Minor RaidDevice State this 0 3 4 0 active sync /dev/hda4 0 0 3 4 0 active sync /dev/hda4 1 1 0 0 1 faulty removed 2 2 33 4 2 active sync /dev/hde4 3 3 34 4 3 active sync /dev/hdg4 helix:~# mdadm --examine /dev/hde3 /dev/hde3: Magic : a92b4efc Version : 00.90.00 UUID : f0ed99aa:a959ca9d:6806265f:a9f9a2da Creation Time : Tue May 8 23:07:00 2007 Raid Level : raid5 Device Size : 173076160 (165.06 GiB 177.23 GB) Array Size : 519228480 (495.17 GiB 531.69 GB) Raid Devices : 4 Total Devices : 4 Preferred Minor : 1 Update Time : Tue May 8 23:07:00 2007 State : clean Active Devices : 3 Working Devices : 3 Failed Devices : 1 Spare Devices : 0 Checksum : ec46fe16 - correct Events : 0.1 Layout : left-symmetric Chunk Size : 64K Number Major Minor RaidDevice State this 2 33 3 2 active sync /dev/hde3 0 0 3 3 0 active sync /dev/hda3 1 1 0 0 1 faulty 2 2 33 3 2 active sync /dev/hde3 3 3 34 3 3 active sync /dev/hdg3 helix:~# mdadm --examine /dev/hde4 /dev/hde4: Magic : a92b4efc Version : 00.90.00 UUID : 4ec47a27:9268fe7d:ee4e9520:8f860d8f Creation Time : Tue May 8 23:04:04 2007 Raid Level : raid5 Device Size : 2441792 (2.33 GiB 2.50 GB) Array Size : 7325376 (6.99 GiB 7.50 GB) Raid Devices : 4 Total Devices : 3 Preferred Minor : 0 Update Time : Tue May 8 23:05:00 2007 State : clean Active Devices : 3 Working Devices : 3 Failed Devices : 1 Spare Devices : 0 Checksum : 94d63e52 - correct Events : 0.4 Layout : left-symmetric Chunk Size : 64K Number Major Minor RaidDevice State this 2 33 4 2 active sync /dev/hde4 0 0 3 4 0 active sync /dev/hda4 1 1 0 0 1 faulty removed 2 2 33 4 2 active sync /dev/hde4 3 3 34 4 3 active sync /dev/hdg4 helix:~# mdadm --examine /dev/hdg3 /dev/hdg3: Magic : a92b4efc Version : 00.90.00 UUID : f0ed99aa:a959ca9d:6806265f:a9f9a2da Creation Time : Tue May 8 23:07:00 2007 Raid Level : raid5 Device Size : 173076160 (165.06 GiB 177.23 GB) Array Size : 519228480 (495.17 GiB 531.69 GB) Raid Devices : 4 Total Devices : 4 Preferred Minor : 1 Update Time : Tue May 8 23:07:00 2007 State : clean Active Devices : 3 Working Devices : 3 Failed Devices : 1 Spare Devices : 0 Checksum : ec46fe19 - correct Events : 0.1 Layout : left-symmetric Chunk Size : 64K Number Major Minor RaidDevice State this 3 34 3 3 active sync /dev/hdg3 0 0 3 3 0 active sync /dev/hda3 1 1 0 0 1 faulty 2 2 33 3 2 active sync /dev/hde3 3 3 34 3 3 active sync /dev/hdg3 helix:~# mdadm --examine /dev/hdg4 /dev/hdg4: Magic : a92b4efc Version : 00.90.00 UUID : 4ec47a27:9268fe7d:ee4e9520:8f860d8f Creation Time : Tue May 8 23:04:04 2007 Raid Level : raid5 Device Size : 2441792 (2.33 GiB 2.50 GB) Array Size : 7325376 (6.99 GiB 7.50 GB) Raid Devices : 4 Total Devices : 3 Preferred Minor : 0 Update Time : Tue May 8 23:05:00 2007 State : clean Active Devices : 3 Working Devices : 3 Failed Devices : 1 Spare Devices : 0 Checksum : 94d63e55 - correct Events : 0.4 Layout : left-symmetric Chunk Size : 64K Number Major Minor RaidDevice State this 3 34 4 3 active sync /dev/hdg4 0 0 3 4 0 active sync /dev/hda4 1 1 0 0 1 faulty removed 2 2 33 4 2 active sync /dev/hde4 3 3 34 4 3 active sync /dev/hdg4 helix:~# fsck -n /dev/md0 fsck 1.40-WIP (14-Nov-2006) e2fsck 1.40-WIP (14-Nov-2006) Warning! /dev/md0 is mounted. /dev/md0: clean, 38/915712 files, 37680/1831344 blocks helix:~# fsck -n /dev/md1 fsck 1.40-WIP (14-Nov-2006) e2fsck 1.40-WIP (14-Nov-2006) Couldn't find ext2 superblock, trying backup blocks... fsck.ext3: Bad magic number in super-block while trying to open /dev/md1 The superblock could not be read or does not describe a correct ext2 filesystem. If the device is valid and it really contains an ext2 filesystem (and not swap or ufs or something else), then the superblock is corrupt, and you might try running e2fsck with an alternate superblock: e2fsck -b 8193 helix:~#