I have a RAID-5 array of 4x1TB hard disks with one lvm2 partition on Ubuntu Linux 10.04 LTS. One of the disks has failed. I have re-assembled the array without this failed disk but now mdadm --examine claims the array has no superblock and fdisk says it has no partition table. What can I do to recover the data?
# mdadm -D /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Sat Mar 5 14:43:49 2011
Raid Level : raid5
Array Size : 2930276352 (2794.53 GiB 3000.60 GB)
Used Dev Size : 976758784 (931.51 GiB 1000.20 GB)
Raid Devices : 4
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Sat Mar 5 15:06:49 2011
State : clean, degraded
Active Devices : 3
Working Devices : 3
Failed Devices : 1
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Name : boba:1 (local to host boba)
UUID : 52eb4bc9:c3d8aab5:e0699505:e0e1aa05
Events : 18
Number Major Minor RaidDevice State
0 8 1 0 active sync /dev/sda1
1 8 65 1 active sync /dev/sde1
2 8 49 2 active sync /dev/sdd1
3 0 0 3 removed
4 8 17 - faulty spare /dev/sdb1
# mdadm --examine /dev/md0
mdadm: No md superblock detected on /dev/md0.
# fdisk -l /dev/md0
Disk /dev/md0: 3000.6 GB, 3000602984448 bytes
2 heads, 4 sectors/track, 732569088 cylinders
Units = cylinders of 8 * 512 = 4096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 524288 bytes / 1572864 bytes
Disk identifier: 0x00000000
Disk /dev/md0 doesn't contain a valid partition table
# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4] [linear] [multipath] [raid0] [raid1] [raid10]
md0 : active raid5 sdb1[4](F) sda1[0] sdd1[2] sde1[1]
2930276352 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/3] [UUU_]
unused devices: <none>
