Re: raid6 grow "hangs" on 2.6.27 with mounted FS

[roma1390]

roma1390 wrote:
> Neil Brown wrote:
>  > This will only happen on very small arrays that take less than a
>  > couple of seconds for the reshape to complete.  I have a patch for
>  > mdadm which makes it more robust in this situation.  It will be in
>  > future releases.
>  >
>  > Does this explain what is happening to you?
>
> Yes, thanks. May be if I retest this situation with same kernel and 
> limited recovery bandwith, then may be i can't hit same problem again?

Yes limiting speed also is posible workaround for this problem:

  ...
  echo 512 > /sys/block/md2/md/sync_speed_min
  echo 512 > /sys/block/md2/md/sync_speed_max
  mkfs.ext2 /dev/md2
  mount /dev/md2 -t ext2 /mnt
  mdadm --add /dev/md2  /dev/loop5
  mdadm --grow /dev/md2 --raid-devices=5
  ...

Bigger values (like 10000) doesn't help.

Thanks.

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