Use iostat with -p for specific device statistics:
$ iostat -xdm-p sda
[10p] Task A - Monitoring the behaviour
Run iostat -x 1 5.
Considering the last two outputs provided by the previous command, calculate the efficiency of IOPS for each of them. Does the amount of data written per I/O increase or decrease?
How to do:
Divide the kilobytes read (rkB/s) and written (wkB/s) per second by the reads per second (r/s) and the writes per second (w/s).
If you happen to have quite a few loop devices in your iostat output, find out what they are exactly: