Re: indefinite hang when growing/reshaping

[Xiao Ni <xni@redhat.com>]

Hi all

   There is the same problem. I can reproduce with the same steps. And
I can reproduce this in a different way too. I don't know whether it's 
the same problem, but the result is the same.

   The different steps are as follows:

mdadm -CR /dev/md0 -l5 -n7 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1 /dev/sdh1 -x1 /dev/sdi1  --assume-clean --bitmap=internal
mdadm --grow -l0 /dev/md0  --backup-file=tmp0
cat /proc/mdstat 
Personalities : [raid6] [raid5] [raid4] [raid1] [raid0] 
md0 : active raid5 loop3[4] loop2[3] loop1[1] loop0[0]
      2045952 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU]
      [>....................]  reshape =  0.0% (0/1022976) finish=5.8min speed=2818K/sec
      
unused devices: <none>

   There is speed 2818K/sec, but if you look by iostat, there is no speed about the disks.


   And there is a workaround:
   mdadm -CR /dev/md0 -l5 -n7 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1 /dev/sdh1 -x1 /dev/sdi1  --assume-clean --bitmap=internal
   mdadm --grow -l0 /dev/md0

   If we don't specify the backup file. The reshape can finish correctly. 

Best Regards
Xiao

----- Original Message -----
> From: "Chris Murphy" <chris@colorremedies.com>
> To: linux-raid@vger.kernel.org
> Sent: Thursday, December 18, 2014 6:20:50 AM
> Subject: indefinite hang when growing/reshaping
> 
> If this is user error I'd expect a discreet error message, but I don't
> get one, just a hang during the reshape following successful --grow
> command (going from 3x device raid5 to 4x device raid5).
> 
> # cat /proc/mdstat
> Personalities : [raid6] [raid5] [raid4]
> md127 : active raid5 loop3[4] loop2[3] loop1[1] loop0[0]
>       2095104 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU]
>       [>....................]  reshape =  0.0% (0/1047552)
> finish=7.0min speed=2402K/sec
> 
> Reproduces with:
> kernel-3.17.6-300.fc21.x86_64
> mdadm-3.3.2-1.fc21.x86_64
> and
> 3.18.0-2.fc22.i686+debug
> mdadm-3.3.2-1.fc21.i686
> 
> Details are here:
> https://bugzilla.kernel.org/show_bug.cgi?id=89851
> 
> --
> Chris Murphy
> --
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>