When you run ps auxf | grep md, can you see a progress is stuck?
If you find it you can check the reason with crash utility. 


----- Original Message -----

From: "Иван Исаев" <redacted>
To: linux-raid@vger.kernel.org
Sent: Wednesday, November 4, 2015 2:44:10 PM
Subject: Fwd: raid6 stuck at reshape

1.  cat /sys/block/md3/md/sync_max
8192
2. no selinux
3.
after recreate of array:
# mdadm --grow --bitmap=none /dev/md3
# mdadm --grow /dev/md3 --raid-devices=12 --backup-file=/home/raid/md3.backup
mdadm: Need to backup 106496K of critical section..
mdadm: Recording backup file in /run/mdadm failed: File exists
...
# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] [linear]
md3 : active raid6 sdn[11] sdm[10] sdl[9] sdj[8] sdg[7] sdh[6] sdi[5]
sdk[4] sdf[3] sde[2] sdd[1] sdc[0]
      26328453120 blocks super 1.2 level 6, 4096k chunk, algorithm 2
[12/12] [UUUUUUUUUUUU]
      [>....................]  reshape =  0.0% (_4096_/2925383680)
finish=3758695.2min speed=12K/sec

no changes.

2015-11-04 13:25 GMT+07:00 Xiao Ni [off-list ref]:

quoted

Hi

You can check the sync_max whether it's 0.

[root@storageqe-19 ~]# cd /sys/block/md1/md/
[root@storageqe-19 md]# cat sync_max
0

And check selinux:
[root@storageqe-19 ~]# systemctl status mdadm-grow-continue@md1.service
● mdadm-grow-continue@md1.service - Manage MD Reshape on /dev/md1
   Loaded: loaded (/usr/lib/systemd/system/mdadm-grow-continue@.service;
   static; vendor preset: disabled)
   Active: failed (Result: exit-code) since Tue 2015-11-03 03:39:11 EST;
   21h ago
  Process: 2353 ExecStart=/usr/sbin/mdadm --grow --continue /dev/%I
  (code=exited, status=2)
 Main PID: 2353 (code=exited, status=2)

Nov 03 03:39:10 storageqe-19.rhts.eng.bos.redhat.com systemd[1]: Started
Manage MD Reshape on /dev/md1.
Nov 03 03:39:10 storageqe-19.rhts.eng.bos.redhat.com systemd[1]: Starting
Manage MD Reshape on /dev/md1...
Nov 03 03:39:11 storageqe-19.rhts.eng.bos.redhat.com systemd[1]:
mdadm-grow-continue@md1.service: main process exite...ENT
Nov 03 03:39:11 storageqe-19.rhts.eng.bos.redhat.com systemd[1]: Unit
mdadm-grow-continue@md1.service entered failed...te.
Nov 03 03:39:11 storageqe-19.rhts.eng.bos.redhat.com systemd[1]:
mdadm-grow-continue@md1.service failed.
Hint: Some lines were ellipsized, use -l to show in full.

I think this is a selinux-policy problem. And you can try reshape a md
without bitmap.
It can success without bitmap.

----- Original Message -----

quoted

From: "Иван Исаев" <redacted>
To: linux-raid@vger.kernel.org
Sent: Wednesday, November 4, 2015 1:53:17 PM
Subject: raid6 stuck at reshape

1. init state:
md3 : active raid6 sdm[10] sdl[9] sdj[8] sdg[7] sdh[6] sdi[5] sdk[4]
sdf[3] sde[2] sdd[1] sdc[0]
      26328453120 blocks super 1.2 level 6, 4096k chunk, algorithm 2
[11/11] [UUUUUUUUUUU]
      bitmap: 0/22 pages [0KB], 65536KB chunk

2. mdadm /dev/md3 -a /dev/sdn
mdadm --grow /dev/md3 --raid-devices=12
--backup-file=/home/raid/md3.backup

md3 : active raid6 sdn[11] sdm[10] sdl[9] sdj[8] sdg[7] sdh[6] sdi[5]
sdk[4] sdf[3] sde[2] sdd[1] sdc[0]
      26328453120 blocks super 1.2 level 6, 4096k chunk, algorithm 2
[12/12] [UUUUUUUUUUUU]
      [>....................]  reshape =  0.0% (0/2925383680)
finish=3047274.6min speed=0K/sec
      bitmap: 0/22 pages [0KB], 65536KB chunk

# ps aux|grep md3
root      5232 _54.8_  0.0      0     0 ?        R    10:55  56:43
[md3_raid6]
root      6956 _98.4_  0.4  53904 49896 ?        RL   11:01  96:29
mdadm --grow /dev/md3 --raid-devices=12
--backup-file=/home/raid/md3.backup

# cat /sys/block/md3/md/reshape_position
81920

what can I do about it?

P.S. If I stop the array, it can no longer be assembled:
# mdadm -S /dev/md3
# mdadm -A /dev/md3
mdadm: :/dev/md3 has an active reshape - checking if critical section
needs to be restored
mdadm: Failed to restore critical section for reshape, sorry.

mdadm --assemble /dev/md3 -vv --backup-file /home/raid/md3.backup -f
mdadm: looking for devices for /dev/md3
...
mdadm: /dev/sdn is identified as a member of /dev/md3, slot 11.
mdadm: /dev/sdl is identified as a member of /dev/md3, slot 9.
mdadm: /dev/sdg is identified as a member of /dev/md3, slot 7.
mdadm: /dev/sdm is identified as a member of /dev/md3, slot 10.
mdadm: /dev/sdj is identified as a member of /dev/md3, slot 8.
mdadm: /dev/sdk is identified as a member of /dev/md3, slot 4.
mdadm: /dev/sdf is identified as a member of /dev/md3, slot 3.
mdadm: /dev/sdd is identified as a member of /dev/md3, slot 1.
mdadm: /dev/sdi is identified as a member of /dev/md3, slot 5.
mdadm: /dev/sdh is identified as a member of /dev/md3, slot 6.
mdadm: /dev/sde is identified as a member of /dev/md3, slot 2.
mdadm: /dev/sdc is identified as a member of /dev/md3, slot 0.
mdadm: :/dev/md3 has an active reshape - checking if critical section
needs to be restored
mdadm: restoring critical section
mdadm: Error restoring backup from md3.backup
mdadm: Failed to restore critical section for reshape, sorry.

# mdadm --assemble /dev/md3 -vv --invalid-backup -f
...
mdadm: :/dev/md3 has an active reshape - checking if critical section
needs to be restored
mdadm: No backup metadata on device-11
mdadm: Failed to find backup of critical section
mdadm: continuing without restoring backup
mdadm: added /dev/sdd to /dev/md3 as 1
mdadm: added /dev/sde to /dev/md3 as 2
mdadm: added /dev/sdf to /dev/md3 as 3
mdadm: added /dev/sdk to /dev/md3 as 4
mdadm: added /dev/sdi to /dev/md3 as 5
mdadm: added /dev/sdh to /dev/md3 as 6
mdadm: added /dev/sdg to /dev/md3 as 7
mdadm: added /dev/sdj to /dev/md3 as 8
mdadm: added /dev/sdl to /dev/md3 as 9
mdadm: added /dev/sdm to /dev/md3 as 10
mdadm: added /dev/sdn to /dev/md3 as 11
mdadm: added /dev/sdc to /dev/md3 as 0
mdadm: failed to RUN_ARRAY /dev/md3: Invalid argument

I had to create array again.
After that the array is operating normally, but I still can't grow it.

P.S.S. kernel: 3.14.56
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