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