[Wylug-help] Inactive RAID 10 Array - Need More Help Please
Dave Fisher
wylug-help at davefisher.co.uk
Fri Apr 17 00:05:53 UTC 2009
On Tue, Apr 14, 2009 at 11:58:15PM +0100, Chris Davies wrote:
> If you "mdadm --examine --scan -v", and the superblocks are still
> intact, you'll get a dump of something like this (from my RAID 1 setup):
>
> # mdadm --examine --scan -v
> ARRAY /dev/md1 level=raid1 num-devices=2 UUID=...
> devices=/dev/hdc1,/dev/hda1
> ARRAY /dev/md5 level=raid1 num-devices=2 UUID=...
> devices=/dev/hdc5,/dev/hda5
> ARRAY /dev/md6 level=raid0 num-devices=2 UUID=...
> devices=/dev/hdc6,/dev/hda6
> ARRAY /dev/md9 level=raid10 num-devices=4 UUID=...
> devices=/dev/dm-8,/dev/dm-3,/dev/dm-2,/dev/dm-1
I get the following:
$ sudo mdadm --examine --scan -v
ARRAY /dev/md0 level=raid1 num-devices=2 UUID=e1023500:94537d05:cb667a5a:bd8e784b
spares=1 devices=/dev/sde2,/dev/sdd2,/dev/sdc2,/dev/sdb2,/dev/sda2
ARRAY /dev/md1 level=raid10 num-devices=4 UUID=f4ddbd55:206c7f81:b855f41b:37d33d37
spares=1 devices=/dev/sde4,/dev/sdd4,/dev/sdc4,/dev/sdb4,/dev/sda4
Which seems consistent.
N.B. the drive letters are slightly different from my original post, because I
removed an irrelevant drive that had nothing to do with RAID.
> If you see the right devices you should simply be able to restart the array:
>
> # mdadm --assemble /dev/md1 /dev/sd{b,c,d,e,f}4
I did:
$ sudo mdadm --assemble /dev/md1 /dev/sdb4 /dev/sdc4 /dev/sdd4 /dev/sde4
And got the following:
mdadm: /dev/md1 assembled from 3 drives and 1 spare - need all 4 to start it (use --run to insist)
I'm not sure that I fully understand this message, so I'm not going to do
anything more than further diagnoses, until:
1. I do understand that message, and;
2. I have a better understanding of the current state of these devices.
Why is it saying "assembled from 3 drives"?
Both parts ("assembled" and "from 3 drives") are unclear to me.
Hasn't mdadm actually *failed* to assemble?
Is it saying "3 drives", because it's not counting the /dev/sdc4 and the spare
(/dev/sde4)?
I am hoping that the situation is not too bad, e.g. that in the worst case, I can
explicitly fail and remove /dev/sdc4, then rebuild the array with the spare.
The optimist/fantacist in me is hoping that, it may be even simpler, e.g. that
/dev/sdc4 is fine and can be re-incorporated without the need to use the spare.
What, if any, are the risks involved in using the --run option?
What would --run actually do in this case?
The manpage says it will:
"will fully activate a partially assembled md array"
But I'm not sure what "fully activate" or "partially assembled" actually mean.
Dave
------------------------------------------------------------------------------
FURTHER NOTES
As you can see (from the output from mdadm -E, shown below) the disks seem to
be in the same condition described in my original post, i.e. the output from
the first device sees the third device (/dev/sdc4) as "faulty removed", but
none of the others do.
The all see /dev/sdc4 as "active synch".
$ sudo mdadm -E /dev/sda4
[sudo] password for davef:
/dev/sda4:
Magic : a92b4efc
Version : 00.90.00
UUID : f4ddbd55:206c7f81:b855f41b:37d33d37
Creation Time : Tue May 6 02:06:45 2008
Raid Level : raid10
Used Dev Size : 965883904 (921.14 GiB 989.07 GB)
Array Size : 1931767808 (1842.28 GiB 1978.13 GB)
Raid Devices : 4
Total Devices : 5
Preferred Minor : 1
Update Time : Tue Apr 14 00:45:27 2009
State : active
Active Devices : 3
Working Devices : 4
Failed Devices : 1
Spare Devices : 1
Checksum : 7a3576c1 - correct
Events : 221
Layout : near=2, far=1
Chunk Size : 64K
Number Major Minor RaidDevice State
this 0 8 20 0 active sync /dev/sdb4
0 0 8 20 0 active sync /dev/sdb4
1 1 8 36 1 active sync /dev/sdc4
2 2 0 0 2 faulty removed
3 3 8 68 3 active sync /dev/sde4
4 4 8 84 4 spare
$ sudo mdadm -E /dev/sdb4
/dev/sdb4:
Magic : a92b4efc
Version : 00.90.00
UUID : f4ddbd55:206c7f81:b855f41b:37d33d37
Creation Time : Tue May 6 02:06:45 2008
Raid Level : raid10
Used Dev Size : 965883904 (921.14 GiB 989.07 GB)
Array Size : 1931767808 (1842.28 GiB 1978.13 GB)
Raid Devices : 4
Total Devices : 5
Preferred Minor : 1
Update Time : Tue Apr 14 00:44:13 2009
State : active
Active Devices : 4
Working Devices : 5
Failed Devices : 0
Spare Devices : 1
Checksum : 7a35767a - correct
Events : 219
Layout : near=2, far=1
Chunk Size : 64K
Number Major Minor RaidDevice State
this 1 8 36 1 active sync /dev/sdc4
0 0 8 20 0 active sync /dev/sdb4
1 1 8 36 1 active sync /dev/sdc4
2 2 8 52 2 active sync /dev/sdd4
3 3 8 68 3 active sync /dev/sde4
4 4 8 84 4 spare
$ sudo mdadm -E /dev/sdc4
/dev/sdc4:
Magic : a92b4efc
Version : 00.90.00
UUID : f4ddbd55:206c7f81:b855f41b:37d33d37
Creation Time : Tue May 6 02:06:45 2008
Raid Level : raid10
Used Dev Size : 965883904 (921.14 GiB 989.07 GB)
Array Size : 1931767808 (1842.28 GiB 1978.13 GB)
Raid Devices : 4
Total Devices : 5
Preferred Minor : 1
Update Time : Tue Apr 14 00:44:13 2009
State : active
Active Devices : 4
Working Devices : 5
Failed Devices : 0
Spare Devices : 1
Checksum : 7a35768c - correct
Events : 219
Layout : near=2, far=1
Chunk Size : 64K
Number Major Minor RaidDevice State
this 2 8 52 2 active sync /dev/sdd4
0 0 8 20 0 active sync /dev/sdb4
1 1 8 36 1 active sync /dev/sdc4
2 2 8 52 2 active sync /dev/sdd4
3 3 8 68 3 active sync /dev/sde4
4 4 8 84 4 spare
$ sudo mdadm -E /dev/sdd4
/dev/sdd4:
Magic : a92b4efc
Version : 00.90.00
UUID : f4ddbd55:206c7f81:b855f41b:37d33d37
Creation Time : Tue May 6 02:06:45 2008
Raid Level : raid10
Used Dev Size : 965883904 (921.14 GiB 989.07 GB)
Array Size : 1931767808 (1842.28 GiB 1978.13 GB)
Raid Devices : 4
Total Devices : 5
Preferred Minor : 1
Update Time : Tue Apr 14 00:44:13 2009
State : active
Active Devices : 4
Working Devices : 5
Failed Devices : 0
Spare Devices : 1
Checksum : 7a35769e - correct
Events : 219
Layout : near=2, far=1
Chunk Size : 64K
Number Major Minor RaidDevice State
this 3 8 68 3 active sync /dev/sde4
0 0 8 20 0 active sync /dev/sdb4
1 1 8 36 1 active sync /dev/sdc4
2 2 8 52 2 active sync /dev/sdd4
3 3 8 68 3 active sync /dev/sde4
4 4 8 84 4 spare
$ sudo mdadm -E /dev/sde4
/dev/sde4:
Magic : a92b4efc
Version : 00.90.00
UUID : f4ddbd55:206c7f81:b855f41b:37d33d37
Creation Time : Tue May 6 02:06:45 2008
Raid Level : raid10
Used Dev Size : 965883904 (921.14 GiB 989.07 GB)
Array Size : 1931767808 (1842.28 GiB 1978.13 GB)
Raid Devices : 4
Total Devices : 5
Preferred Minor : 1
Update Time : Fri Apr 10 16:43:47 2009
State : clean
Active Devices : 4
Working Devices : 5
Failed Devices : 0
Spare Devices : 1
Checksum : 7a31126a - correct
Events : 218
Layout : near=2, far=1
Chunk Size : 64K
Number Major Minor RaidDevice State
this 4 8 84 4 spare
0 0 8 20 0 active sync /dev/sdb4
1 1 8 36 1 active sync /dev/sdc4
2 2 8 52 2 active sync /dev/sdd4
3 3 8 68 3 active sync /dev/sde4
4 4 8 84 4 spare
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