Unable to assemble a multi-degraded Raid5...
am 24.11.2010 11:36:05 von Andrea GelminiGoodmorning,
thanks a lot for your daily support on the mailing list.
I've got a problem. Not a big deal (all the important data are
daily backuped), but
I ask your help 'cause I would like to understand what I do wrong.
Well, I have an old raid5 made by 4 disks (it has growed and
reshaped, time to time,
without problem). You can find detail at the end.
I want copy/clone data on a new set of drive.
Because number-of-sata-ports-problem I unplagged one of the four.
So I run a degraded raid, but forcing (from now on) the mount of the
filesystem in readonly mode.
After hours of copy, two disks failed (so, 3 degraded minus 2 faults!).
That's a problem, of course.
So I try to force an assemble, but it always miss, even re-plugging
the first one.
I just use the --assemble in such way (as in recipes):
mdadm --assemble --auto=yes --force /dev/md0 /dev/sd[abdf]
mdadm: failed to add /dev/sdd to /dev/md0: Invalid argument
mdadm: failed to add /dev/sda to /dev/md0: Invalid argument
mdadm: /dev/md0 assembled from 2 drives - not enough to start the array.
And in dmesg:
[ 610.072698] md: md0 stopped.
[ 610.080432] md: bind
[ 610.080576] md: bind
[ 610.080710] md: sdd has same UUID but different superblock to sdf
[ 610.080714] md: sdd has different UUID to sdf
[ 610.080716] md: export_rdev(sdd)
[ 610.080885] md: sda has same UUID but different superblock to sdf
[ 610.080888] md: sda has different UUID to sdf
[ 610.080890] md: export_rdev(sda)
Well. I can read the discs with dd to /dev/null (to be sure about
no hardware failure).
Now, playing with the set of --assemble, --run and --force I had
some note from
mdadm about shame-on-me-I-didn't-write-down-what-it-did
something like a forced advance in events numbers, maybe?
(ok, you can hate me).
Also, I'm using latest Ubuntu server. I also try mdadm from git repository.
Thanks a lot for your precious help and time,
Andrea
---------------------------------------------------
/dev/sda:
Magic : a92b4efc
Version : 00.90.00
UUID : 9969bb23:1ed5d50b:af41a831:27732f7b
Creation Time : Fri Mar 21 02:33:34 2008
Raid Level : raid5
Used Dev Size : 976762368 (931.51 GiB 1000.20 GB)
Array Size : 2930287104 (2794.54 GiB 3000.61 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Update Time : Tue Nov 23 01:51:39 2010
State : clean
Internal Bitmap : present
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Checksum : 72bd657 - correct
Events : 58218
Layout : left-symmetric
Chunk Size : 256K
Number Major Minor RaidDevice State
this 0 8 0 0 active sync /dev/sda
0 0 8 0 0 active sync /dev/sda
1 1 8 16 1 active sync /dev/sdb
2 2 8 48 2 active sync /dev/sdd
3 3 8 32 3 active sync /dev/sdc
/dev/sdb:
Magic : a92b4efc
Version : 00.90.00
UUID : 9969bb23:1ed5d50b:af41a831:27732f7b
Creation Time : Fri Mar 21 02:33:34 2008
Raid Level : raid5
Used Dev Size : 976762368 (931.51 GiB 1000.20 GB)
Array Size : 2930287104 (2794.54 GiB 3000.61 GB)
Raid Devices : 4
Total Devices : 3
Preferred Minor : 1
Update Time : Wed Nov 24 02:39:56 2010
State : clean
Internal Bitmap : present
Active Devices : 2
Working Devices : 2
Failed Devices : 1
Spare Devices : 0
Checksum : 72d336d - correct
Events : 58218
Layout : left-symmetric
Chunk Size : 256K
Number Major Minor RaidDevice State
this 1 8 16 1 active sync /dev/sdb
0 0 0 0 0 removed
1 1 8 16 1 active sync /dev/sdb
2 2 8 80 2 active sync /dev/sdf
3 3 0 0 3 active sync
/dev/sdd:
Magic : a92b4efc
Version : 00.90.00
UUID : 9969bb23:1ed5d50b:af41a831:27732f7b
Creation Time : Fri Mar 21 02:33:34 2008
Raid Level : raid5
Used Dev Size : 976762368 (931.51 GiB 1000.20 GB)
Array Size : 2930287104 (2794.54 GiB 3000.61 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Update Time : Tue Nov 23 01:51:39 2010
State : clean
Internal Bitmap : present
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Checksum : 72bd67d - correct
Events : 58218
Layout : left-symmetric
Chunk Size : 256K
Number Major Minor RaidDevice State
this 3 8 32 3 active sync /dev/sdc
0 0 8 0 0 active sync /dev/sda
1 1 8 16 1 active sync /dev/sdb
2 2 8 48 2 active sync /dev/sdd
3 3 8 32 3 active sync /dev/sdc
/dev/sdf:
Magic : a92b4efc
Version : 00.90.00
UUID : 9969bb23:1ed5d50b:af41a831:27732f7b
Creation Time : Fri Mar 21 02:33:34 2008
Raid Level : raid5
Used Dev Size : 976762368 (931.51 GiB 1000.20 GB)
Array Size : 2930287104 (2794.54 GiB 3000.61 GB)
Raid Devices : 4
Total Devices : 3
Preferred Minor : 1
Update Time : Wed Nov 24 02:39:56 2010
State : clean
Internal Bitmap : present
Active Devices : 2
Working Devices : 2
Failed Devices : 1
Spare Devices : 0
Checksum : 72d33b2 - correct
Events : 58218
Layout : left-symmetric
Chunk Size : 256K
Number Major Minor RaidDevice State
this 2 8 80 2 active sync /dev/sdf
0 0 0 0 0 removed
1 1 8 16 1 active sync /dev/sdb
2 2 8 80 2 active sync /dev/sdf
3 3 0 0 3 faulty removed
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