iostat –kx 2 50

-k     Display  statistics  in kilobytes per second instead of blocks per second.  Data displayed are valid only
              with kernels 2.4 and newer.
-x     Display extended statistics.  This option is exclusive of the -p and -n, and works with post 2.5  kernels
              since  it  needs /proc/diskstats file or a mounted sysfs to get the statistics. This option may also work
              with older kernels (e.g. 2.4) only if extended statistics are available in /proc/partitions  (the  kernel
              needs to be patched for that).

       iostat
              Display a single history since boot report for all CPU and Devices.

       iostat -d 2
              Display a continuous device report at two second intervals.

       iostat -d 2 6
              Display six reports at two second intervals for all devices.

       iostat -x hda hdb 2 6
              Display six reports of extended statistics at two second intervals for devices hda and hdb.

       iostat -p sda 2 6
              Display six reports at two second intervals for device sda and all its partitions (sda1, etc.)