(original article)

Re: Converting RAID5 to RAID6 and other shape changing in md/raid

12 February 2010, 11:16 UTC

I have just started a conversion of a 6 disk 2TB RAID5 to a 8 disk 2TB RAID6 on my system.

The performance during conversion was terrible - 1MB/second. This got me suspicious, as I know the array could perform much better than that.

Issuing "echo 200000 > /sys/block/<mddevice>/md/sync_speed_min" fixed it, as it now reshapes at 20MB/second.

This ofcourse blocks everything else, but issuing an "echo 10000" gives the a fair tradeoff, as the "when idle" system obviously seems to have a problem.

So try this, instead of rebooting.