On Wed, 24 Nov 2010 11:36:05 +0100 Andrea Gelmini <andrea.gelmini@xxxxxxxxx>
wrote:
> Goodmorning,
> 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<sdb>
> [ 610.080576] md: bind<sdf>
> [ 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)
The "but different superblock" is because the 'Preferred minor' is different
for some reason.
You might be able to fix that by stopping the array and then
assembling it again with --update=super-minor.
So
mdadm --assemble --auto=yes --force \
--update=super-minor /dev/md0 /dev/sd[abdf]
NeilBrown
>
> 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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