Re: raid problem

[Stan Hoeppner <stan@hardwarefreak.com>]

On 11/29/2013 4:43 PM, François Patte wrote:
> Bonsoir,
> 
> I have a problem with 2 raid arrays: I have 2 disks (sdc and sdd) in
> raid1 arrays.
> 
> One disk (sdc) failed and I replaced it by a new one. Copying the
> partition table from sdd disk using sfdisk:
> 
> sfdisk -d /dev/sdd | sfdisk /dev/sdc
> 
> then I "added" the 2 partitions (sdc1 and sdc3) to the arrays md0 and md1:
> 
> mdadm --add /dev/md0 /dev/sdc1
> 
> mdadm --add /dev/md1 /dev/sdc3
> 
> There were no problem with the md0 array:
> 
> 
> cat /proc/mdstat gives:
> 
> md0 : active raid1 sdc1[1] sdd1[0]
>       1052160 blocks [2/2] [UU]
> 
> 
> But for the md1 array, I get:
> 
> md1 : active raid1 sdc3[2](S) sdd3[0]
>       483138688 blocks [2/1] [U_]
> 
> 
> And mdadm --detail /dev/md1 returns:
> 
> /dev/md1:
>         Version : 0.90
>   Creation Time : Sat Mar  7 11:48:30 2009
>      Raid Level : raid1
>      Array Size : 483138688 (460.76 GiB 494.73 GB)
>   Used Dev Size : 483138688 (460.76 GiB 494.73 GB)
>    Raid Devices : 2
>   Total Devices : 2
> Preferred Minor : 1
>     Persistence : Superblock is persistent
> 
>     Update Time : Fri Nov 29 21:23:25 2013
>           State : clean, degraded
>  Active Devices : 1
> Working Devices : 2
>  Failed Devices : 0
>   Spare Devices : 1
> 
>            UUID : 2e8294de:9b0d8d96:680a5413:2aac5c13
>          Events : 0.72076
> 
>     Number   Major   Minor   RaidDevice State
>        0       8       51        0      active sync   /dev/sdd3
>        2       0        0        2      removed
> 
>        2       8       35        -      spare   /dev/sdc3
> 
> While mdadm --examine /dev/sdc3 returns:
> 
> /dev/sdc3:
>           Magic : a92b4efc
>         Version : 0.90.00
>            UUID : 2e8294de:9b0d8d96:680a5413:2aac5c13
>   Creation Time : Sat Mar  7 11:48:30 2009
>      Raid Level : raid1
>   Used Dev Size : 483138688 (460.76 GiB 494.73 GB)
> 
> 
>      Array Size : 483138688 (460.76 GiB 494.73 GB)
>    Raid Devices : 2
>   Total Devices : 2
> Preferred Minor : 1
> 
>     Update Time : Fri Nov 29 23:03:41 2013
>           State : clean
>  Active Devices : 1
> Working Devices : 2
>  Failed Devices : 1
>   Spare Devices : 1
>        Checksum : be8bd27f - correct
>          Events : 72078
> 
> 
>       Number   Major   Minor   RaidDevice State
> this     2       8       35        2      spare   /dev/sdc3
> 
>    0     0       8       51        0      active sync   /dev/sdd3
>    1     1       0        0        1      faulty removed
>    2     2       8       35        2      spare   /dev/sdc3
> 
> 
> What is the problem? And how can I recover a correct md1 array?

IIRC Linux md rebuilds multiple degraded arrays sequentially, not in
parallel.  This is due to system performance impact and other reasons.
When the rebuild of md0 is finished, the rebuild of md1/sdc3 should
start automatically.  If this did not occur please let us know and we'll
go from there.

-- 
Stan