Nasser Heidari

2009-07-08

iostat – Linux Disk utilization

Filed under: Linux — Nasser Heidari @ 06:18

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%.

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