Sorry, this is going to be a rather long post...Here's the situation; I
have 4 IDE disks from an old snap server which fails to mount the raid
array. We believe there is a controller error on the SNAP so we've put
them in another box running CentOS 5 and can see the disks OK.
hda thru hdd looks like this
Disk /dev/hdd: 185.2 GB, 185283624960 bytes
255 heads, 63 sectors/track, 22526 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/hdd1 * 1 2 16041+ 83 Linux
/dev/hdd2 3 70 546210 83 Linux
/dev/hdd3 71 138 546210 5 Extended
/dev/hdd4 139 21781 173844468 83 Linux
/dev/hdd5 71 104 273104+ 83 Linux
/dev/hdd6 105 138 273104+ 83 Linux
I can mount hdX1 and hdX2 (hdx2 is xfs) on all disks.
Now /etc/raidtab (from one of the hdx2 partions) has the following entry
which I'd like to re-create on the CentOS box
raiddev /dev/md0
raid-level 5
nr-raid-disks 4
nr-spare-disks 0
persistent-superblock 1
chunk-size 64
device /dev/hda4
raid-disk 0
device /dev/hdc4
raid-disk 1
device /dev/hde4
raid-disk 2
device /dev/hdg4
raid-disk 3
I've also checked the superblocks
/dev/hda4:
Magic : a92b4efc
Version : 00.90.00
UUID : a72e334f:a9ccba81:bba665d8:82a3c378
Creation Time : Mon Jun 30 12:00:28 2003
Raid Level : raid5
Used Dev Size : 173844352 (165.79 GiB 178.02 GB)
Array Size : 521533056 (497.37 GiB 534.05 GB)
Raid Devices : 4
Total Devices : 3
Preferred Minor : 0
Update Time : Tue May 19 21:40:43 2009
State : active
Active Devices : 2
Working Devices : 2
Failed Devices : 1
Spare Devices : 0
Checksum : cbe14089 - correct
Events : 0.22
Layout : left-asymmetric
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 22 4 1 faulty /dev/hdc4
2 2 0 0 2 faulty removed
3 3 34 4 3 active sync
/dev/hdb4:
Magic : a92b4efc
Version : 00.90.00
UUID : a72e334f:a9ccba81:bba665d8:82a3c378
Creation Time : Mon Jun 30 12:00:28 2003
Raid Level : raid5
Used Dev Size : 173844352 (165.79 GiB 178.02 GB)
Array Size : 521533056 (497.37 GiB 534.05 GB)
Raid Devices : 4
Total Devices : 3
Preferred Minor : 0
Update Time : Sat Aug 2 19:26:28 2008
State : active
Active Devices : 3
Working Devices : 3
Failed Devices : 0
Spare Devices : 0
Checksum : ca62ce2c - correct
Events : 0.21
Layout : left-asymmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
this 1 22 4 1 active sync /dev/hdc4
0 0 3 4 0 active sync /dev/hda4
1 1 22 4 1 active sync /dev/hdc4
2 2 0 0 2 faulty removed
3 3 34 4 3 active sync
/dev/hdc4:
Magic : a92b4efc
Version : 00.90.00
UUID : a72e334f:a9ccba81:bba665d8:82a3c378
Creation Time : Mon Jun 30 12:00:28 2003
Raid Level : raid5
Used Dev Size : 173844352 (165.79 GiB 178.02 GB)
Array Size : 521533056 (497.37 GiB 534.05 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Update Time : Sun Jul 22 22:33:00 2007
State : active
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Checksum : c871f493 - correct
Events : 0.18
Layout : left-asymmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
this 2 33 4 2 active sync
0 0 3 4 0 active sync /dev/hda4
1 1 22 4 1 active sync /dev/hdc4
2 2 33 4 2 active sync
3 3 34 4 3 active sync
/dev/hdd4:
Magic : a92b4efc
Version : 00.90.00
UUID : a72e334f:a9ccba81:bba665d8:82a3c378
Creation Time : Mon Jun 30 12:00:28 2003
Raid Level : raid5
Used Dev Size : 173844352 (165.79 GiB 178.02 GB)
Array Size : 521533056 (497.37 GiB 534.05 GB)
Raid Devices : 4
Total Devices : 3
Preferred Minor : 0
Update Time : Sat Aug 2 19:26:28 2008
State : active
Active Devices : 3
Working Devices : 3
Failed Devices : 0
Spare Devices : 0
Checksum : ca62ce3c - correct
Events : 0.21
Layout : left-asymmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
this 3 34 4 3 active sync
0 0 3 4 0 active sync /dev/hda4
1 1 22 4 1 active sync /dev/hdc4
2 2 0 0 2 faulty removed
3 3 34 4 3 active sync
This is my fist stab and re-assembling an array after moving the disks
so I though I'd double check how I would go about re-assembling this Can
I simply do
mdadm --assemble --scan
? Or do I need to reset the superblocks and re-assemble in degraded mode
somehow?
TIA
Dan