> using iostat from systat package?
sudo yum install sysstat
(not the two 's' in the middle)
For example:
iostat -m 5 /dev/md{0,1} /dev/sd{a,b,c,d,e}
-m : output in megabytes
5: every 5s
/dev/md{0,1} /dev/sd{a,b,c,d,e} : the various drives to filter (no
such argument will show them all)