I had a raid 5 array that was working, configured as:
DEVICE partitions
ARRAY /dev/md0 level=raid5 num-devices=4 UUID=641451fb:1b26c30d:1570e92e:7cb2119d
devices=/dev/hdc1,/dev/hdd1,/dev/sda1,/dev/sdb1
I got a load of messages on the console:
Apr 15 20:19:58 server1 kernel: md: md0: sync done.
Apr 15 20:19:58 server1 kernel: md: syncing RAID array md0
Apr 15 20:19:58 server1 kernel: md: minimum _guaranteed_ reconstruction speed: 1000 KB/sec/disc.
Apr 15 20:19:58 server1 kernel: md: using maximum available idle IO bandwith (but not more than 200000 KB/sec) for reconstruction.
Apr 15 20:19:58 server1 kernel: md: using 128k window, over a total of 244195904 blocks.
Apr 15 20:19:58 server1 kernel: md: md0: sync done.
Apr 15 20:19:58 server1 kernel: md: syncing RAID array md0
Apr 15 20:19:58 server1 kernel: md: minimum _guaranteed_ reconstruction speed: 1000 KB/sec/disc.
Apr 15 20:19:58 server1 kernel: md: using maximum available idle IO bandwith (but not more than 200000 KB/sec) for reconstruction.
Apr 15 20:19:58 server1 kernel: md: using 128k window, over a total of 244195904 blocks.
Apr 15 20:19:58 server1 kernel: md: md0: sync done.
The machine was unusable so I rebooted now my array is not working:
mdadm -D /dev/md0
/dev/md0:
Version : 00.90.01
Creation Time : Sat Apr 8 00:29:58 2006
Raid Level : raid5
Device Size : 244195904 (232.88 GiB 250.06 GB)
Raid Devices : 4
Total Devices : 2
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Sat Apr 15 20:21:17 2006
State : active, degraded
Active Devices : 1
Working Devices : 2
Failed Devices : 0
Spare Devices : 1
Layout : left-symmetric
Chunk Size : 64K
UUID : 641451fb:1b26c30d:1570e92e:7cb2119d
Events : 0.890872
Number Major Minor RaidDevice State
0 22 1 0 active sync /dev/hdc1
1 22 65 1 spare rebuilding /dev/hdd1
2 0 0 - removed
3 0 0 - removed
Thanks