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
on 5-20-2009 8:32 AM Daniel Bird spake the following:> 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 > > DanAre you sure that all the disks are in the same position that they were in when removed from the snap server? IE... hda on the snap is still hda on the new controller. If so, you could try the assemble command. Otherwise you will have to do some creative work to get it going. But from the above superblocks, the array is very dirty, and some drives have different array status, so you might have to force things along. If this data is critical, I would dd the drives onto other hardware and experiment there, or at least dd the drives to image files and try those. If you succeed, you can backup the data and restore later. If you fail with the original drives, you might render the array unrecoverable. -------------- next part -------------- A non-text attachment was scrubbed... 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> Are you sure that all the disks are in the same position that they were in > when removed from the snap server?The drives are the same position , i.e hda is hda and hdb is hdb etc, but hdc and hdd were hde and hdg previously. Does that matter?> If you fail with the original drives, you might render the array > unrecoverable. >dd is a good idea. I'll dd these disks and try with the images. Cheers,> > ------------------------------------------------------------------------ > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos >-- ____________________________________ Daniel Bird Network and Systems Manager Computing Services Information Services St. George's, University Of London Cranmer Terrace London SW17 0RE Email: dbird at sgul.ac.uk Direct Dial: +44 20 8725 2897 Fax: +44 20 8725 3583