iostat syntax for disk utilization report
iostat -d -x interval count
* -d : Display the device utilization report (d == disk)
* -x : Display extended statistics including disk utilization
* interval : It is time period in seconds between two samples . iostat 2 will give data at each 2 seconds interval.
* count : It is the number of times the data is needed . iostat 2 5 will give data at 2 seconds interval 5 times
# iostat -d -x 4 5
Display 4 reports of extended statistics at 5 second intervals for disk .
Linux 2.6.18-92.1.13.el5 (Zapata) 07/08/2009 Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util cciss/c0d0 0.16 46.57 1.01 13.54 43.14 67.34 7.59 0.07 5.11 3.85 5.61 Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util cciss/c0d0 0.00 1067.83 0.00 160.85 0.00 9829.43 61.11 41.20 256.17 2.15 34.61 Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util cciss/c0d0 0.00 4.00 0.00 1.50 0.00 44.00 29.33 0.01 7.00 7.00 1.05 Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util cciss/c0d0 0.00 13.25 0.00 3.75 0.00 136.00 36.27 0.03 8.20 7.33 2.75 Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util cciss/c0d0 0.00 4.75 0.00 1.25 0.00 48.00 38.40 0.01 6.00 6.00 0.75
* rrqm/s : The number of read requests merged per second that were queued to the hard disk
* wrqm/s : The number of write requests merged per second that were queued to the hard disk
* r/s : The number of read requests per second
* w/s : The number of write requests per second
* rsec/s : The number of sectors read from the hard disk per second
* wsec/s : The number of sectors written to the hard disk per second
* avgrq-sz : The average size (in sectors) of the requests that were issued to the device.
* avgqu-sz : The average queue length of the requests that were issued to the device
* await : The average time (in milliseconds) for I/O requests issued to the device to be served. This includes the time spent by the requests in queue and the time spent servicing them.
* svctm : The average service time (in milliseconds) for I/O requests that were issued to the device
* %util : Percentage of CPU time during which I/O requests were issued to the device (bandwidth utilization for the device). Device saturation occurs when this value is close to 100%.
