Bug#495580: mdadm: 4 disk raid10 with 1 active and 3 spare possible
Neil Brown
neilb at suse.de
Mon Oct 13 04:50:59 UTC 2008
On Wednesday August 20, fzielcke at z-51.de wrote:
>
> The current Debian sid kernel 2.6.26-2 does sync the disks if I add
> them.
> I tried now even the newer 2.6.27-rc3-git6 out, because it has a few MD
> changes.
> That one adds the disks only as `spare' but does not start a resync.
I cannot reproduce this.
This is surprising though:
> fz-vm:~# cat /proc/mdstat
> Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] [multipath]
> md0 : active raid10 sdc1[4](S) sdf1[3] sde1[2] sdd1[1]
> 16771584 blocks 64K chunks 2 near-copies [4/3] [_UUU]
>
> unused devices: <none>
Here there is one failed device. There is one spare but the array
isn't resyncing.
And...
> fz-vm:~# mdadm -Q --detail /dev/md0
> /dev/md0:
> Version : 00.90
> Creation Time : Wed Aug 20 09:03:27 2008
> Raid Level : raid10
> Array Size : 16771584 (15.99 GiB 17.17 GB)
> Used Dev Size : 8385792 (8.00 GiB 8.59 GB)
> Raid Devices : 4
> Total Devices : 4
> Preferred Minor : 0
> Persistence : Superblock is persistent
>
> Update Time : Wed Aug 20 09:07:32 2008
> State : clean, degraded
> Active Devices : 3
> Working Devices : 4
> Failed Devices : 0
> Spare Devices : 1
>
> Layout : near=2, far=1
> Chunk Size : 64K
>
> UUID : 04e72c15:980e57a0:89ccbef7:ff5abfb0 (local to host fz-vm)
> Events : 0.10
>
> Number Major Minor RaidDevice State
> 0 0 0 0 removed
> 1 8 49 1 active sync /dev/sdd1
> 2 8 65 2 active sync /dev/sde1
> 3 8 81 3 active sync /dev/sdf1
>
> 4 8 33 - spare /dev/sdc1
> fz-vm:~# cat /proc/mdstat
> Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] [multipath]
> md0 : active raid10 sdd1[4](S) sdc1[5](S) sdf1[3] sde1[2]
> 16771584 blocks 64K chunks 2 near-copies [4/2] [__UU]
Here there are two failed devices. What happened?
Do the kernel logs show anything between these two "cat /proc/mdstat"s?
NeilBrown
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