On 03/15/2014 12:28 AM, Scott D'Vileskis wrote:

However, when I started a format of an unrelated partition on
/dev/sda, the RAID 'recovery' disk-replacement completely stopped. I
suspect the RAID rebuild mechanism is pausing because of the activity
on /dev/sda.

I monkeyed with
echo 90000 > speed_limit_min
and now I get 10 second bursts of 20-100MB/sec every 30 seconds or so,
so at least the jobs will finish in parallel..

I feel the RAID --replace option should only concern itself with the
two disks involved not get caught up because of activity on another
disk. Is this a bug?

This is deliberate, and in my opinion, desirable.  Same thing happens
when doing a check or any kind of rebuild on multiple arrays that use
partitions on shared underlying devices.  If you don't limit the raid
background activity, the extra seek load on the devices can severely cut
performance, especially on spinning rust.

Phil