The iostat utility is used to gather performance statistics for partitions or devices. You may need to install the sysstat package first before you use the iostat command.
$ yum install sysstat
To run iostat simply type:
$ iostat
You can tell iostat to run continuously by setting the an interval, in minutes and number of intervals to run. The below example specifies an interval of 30 seconds to be run 10 times.
$ iostat 30 10
You can also just look at one device at a time by using the -p <device> option.
$ iostat -p /dev/sda
To display only CPU usage use the -c option and to display only the device utilization report use the -d option.
$ iostat -c
$ iostat -d
To display the information in kilobytes per second rather then blocks per second use the -k option.
$ iostat -k
To display extended statistics use -x option.
$ iostat -x
Display a continuous device report at two second intervals.
$ iostat -d 2
Display six reports at two second intervals for all devices.
$ iostat -d 2 6
Display six reports of extended statistics at two second intervals for devices hda and hdb.
$ iostat -x hda hdb 2 6
Display six reports at two second intervals for device sda and all its partitions (sda1, etc.)
$ iostat -p sda 2 6