Re: Raid 5 to raid 6 reshape failure after reboot

[Guy Martin <gmsoft@tuxicoman.be>]

Neil,

While redoing the reboot test, I've also noticed this :
When I first issue the --grow command, I see the following in dmesg :
[192752.106467] md: reshape of RAID array md0
[192752.106473] md: minimum _guaranteed_  speed: 200000 KB/sec/disk.
[192752.106479] md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for reshape.

The minimum guaranteed speed should be 1000KB/sec according to the
entry in /proc/sys/dev/raid/speed_limit_min.

Also, the performances are not really good. I have about 400K/sec according to /proc/mdstat.

Now, if I stop the array and assemble it again, things are better. The output in dmesg displays the correct value :
[193138.646204] md: minimum _guaranteed_  speed: 1000 KB/sec/disk.
[193138.646210] md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for reshape.

And perf are much better, I now get ~1500K/s which shrinks the time of the reshape from ~2 weeks to 'only' a few days.

Any thoughts ?

HTH,
  Guy


On Thu, 22 Oct 2009 10:44:53 +1100
Neil Brown <neilb@suse.de> wrote:


> Thanks for helping make mdadm even better!
> 
> NeilBrown
>