On Tue, 18 Sep 2012 11:04:36 +0600 Roman Mamedov <rm@xxxxxxxxxx> wrote:
> Hello,
>
> Summary:
>
> After removing a disk via "want_replacement", disk count in /proc/mdstat is
> wrong ("[5/4]", not "[5/5]" as it should be).
>
> More details below:
>
> ----
>
> # mdadm --add /dev/md0 /dev/sdb1
> mdadm: added /dev/sdb1
>
> # mdadm --detail /dev/md0
> /dev/md0:
> Version : 1.2
> Creation Time : Wed May 25 00:07:38 2011
> Raid Level : raid5
> Array Size : 3907003136 (3726.01 GiB 4000.77 GB)
> Used Dev Size : 976750784 (931.50 GiB 1000.19 GB)
> Raid Devices : 5
> Total Devices : 6
> Persistence : Superblock is persistent
>
> Intent Bitmap : Internal
>
> Update Time : Tue Sep 18 01:01:38 2012
> State : active
> Active Devices : 5
> Working Devices : 6
> Failed Devices : 0
> Spare Devices : 1
>
> Layout : left-symmetric
> Chunk Size : 64K
>
> Name : avdeb:0 (local to host avdeb)
> UUID : b99961fb:ed1f76c8:ec2dad31:6db45332
> Events : 14135
>
> Number Major Minor RaidDevice State
> 0 8 65 0 active sync /dev/sde1
> 6 8 33 1 active sync /dev/sdc1
> 3 8 81 2 active sync /dev/sdf1
> 4 8 49 3 active sync /dev/sdd1
> 5 8 97 4 active sync /dev/sdg1
>
> 7 8 17 - spare /dev/sdb1
>
> # echo want_replacement > /sys/block/md0/md/dev-sde1/state
>
> // It's rebuilding:
>
> # cat /proc/mdstat
> Personalities : [raid6] [raid5] [raid4]
> md0 : active raid5 sdb1[7](R) sde1[0] sdg1[5] sdd1[4] sdf1[3] sdc1[6]
> 3907003136 blocks super 1.2 level 5, 64k chunk, algorithm 2 [5/5] [UUUUU]
> [>....................] recovery = 0.1% (1724936/976750784) finish=150.7min speed=107808K/sec
> bitmap: 0/4 pages [0KB], 131072KB chunk
>
> // Rebuild finished:
>
> # cat /proc/mdstat
> md0 : active raid5 sdb1[7] sde1[0](F) sdg1[5] sdd1[4] sdf1[3] sdc1[6]
> 3907003136 blocks super 1.2 level 5, 64k chunk, algorithm 2 [5/4] [UUUUU]
> bitmap: 0/4 pages [0KB], 131072KB chunk
>
> # mdadm --detail /dev/md0
> /dev/md0:
> Version : 1.2
> Creation Time : Wed May 25 00:07:38 2011
> Raid Level : raid5
> Array Size : 3907003136 (3726.01 GiB 4000.77 GB)
> Used Dev Size : 976750784 (931.50 GiB 1000.19 GB)
> Raid Devices : 5
> Total Devices : 6
> Persistence : Superblock is persistent
>
> Intent Bitmap : Internal
>
> Update Time : Tue Sep 18 04:46:14 2012
> State : active
> Active Devices : 5
> Working Devices : 5
> Failed Devices : 1
> Spare Devices : 0
>
> Layout : left-symmetric
> Chunk Size : 64K
>
> Name : avdeb:0 (local to host avdeb)
> UUID : b99961fb:ed1f76c8:ec2dad31:6db45332
> Events : 14231
>
> Number Major Minor RaidDevice State
> 7 8 17 0 active sync /dev/sdb1
> 6 8 33 1 active sync /dev/sdc1
> 3 8 81 2 active sync /dev/sdf1
> 4 8 49 3 active sync /dev/sdd1
> 5 8 97 4 active sync /dev/sdg1
>
> 0 8 65 - faulty spare /dev/sde1
>
> // Removing sde1:
>
> # mdadm --remove /dev/md0 /dev/sde1
> mdadm: hot removed /dev/sde1 from /dev/md0
>
> // Removed ok:
>
> # mdadm --detail /dev/md0
> /dev/md0:
> Version : 1.2
> Creation Time : Wed May 25 00:07:38 2011
> Raid Level : raid5
> Array Size : 3907003136 (3726.01 GiB 4000.77 GB)
> Used Dev Size : 976750784 (931.50 GiB 1000.19 GB)
> Raid Devices : 5
> Total Devices : 5
> Persistence : Superblock is persistent
>
> Intent Bitmap : Internal
>
> Update Time : Tue Sep 18 08:49:24 2012
> State : active
> Active Devices : 5
> Working Devices : 5
> Failed Devices : 0
> Spare Devices : 0
>
> Layout : left-symmetric
> Chunk Size : 64K
>
> Name : avdeb:0 (local to host avdeb)
> UUID : b99961fb:ed1f76c8:ec2dad31:6db45332
> Events : 14234
>
> Number Major Minor RaidDevice State
> 7 8 17 0 active sync /dev/sdb1
> 6 8 33 1 active sync /dev/sdc1
> 3 8 81 2 active sync /dev/sdf1
> 4 8 49 3 active sync /dev/sdd1
> 5 8 97 4 active sync /dev/sdg1
>
> // In the end /proc/mdstat shows "[5/4]", not "[5/5]":
>
> # cat /proc/mdstat
> md0 : active raid5 sdb1[7] sdg1[5] sdd1[4] sdf1[3] sdc1[6]
> 3907003136 blocks super 1.2 level 5, 64k chunk, algorithm 2 [5/4] [UUUUU]
> bitmap: 0/4 pages [0KB], 131072KB chunk
>
Thanks for the report.
I think that's fixed by:
http://git.neil.brown.name/?p=linux.git;a=commitdiff;h=413c4a33cb3cd1a14431c61fd20904cdb1867d17
which I will hopefully be sending to Linus some time soon.
NeilBrown
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