This affects the minimum and maximum speeds allowed for throttling of reshaping and checking activities of mdadm.
To monitor the current speed
sudo cat /proc/mdstat
To temporarily adjust the speed use the commands below. They will reset to defaults on the next reboot. The speed, x, is a number in kbytes/seconds.
echo x > /proc/sys/dev/raid/speed_limit_min
echo x > /proc/sys/dev/raid/speed_limit_max
To make the change permanent and persist after a reboot modify this file:
Add these lines where the speed, x, is a number in kbytes/seconds.
dev.raid.speed_limit_min = x
dev.raid.speed_limit_max = x