Click this button to go to the index for this section.

iostat(1)
NAME
  iostat - Reports I/O statistics

SYNOPSIS
  iostat [drive...] [interval] [count]

DESCRIPTION
  The iostat command reports the following information:

    ·  For terminals (collectively), the number of characters read and
       written per second.

    ·  For each disk, the number of transfers per second, bytes transferred
       per second (in kilobytes), and the milliseconds per average seek. Not
       all disk drives report seek times.

    ·  For the system, the percentage of time the system has spent in user
       mode, in user mode running low priority (nice) processes, in system
       mode, and idling.

  To compute this information, iostat counts the number of seeks and data
  transfer completions, the number of words transferred for each disk, and
  the collective number of input and output characters for terminals.  Also,
  each sixtieth of a second, iostat examines the state of each disk and makes
  a tally if the disk is active.  From these numbers and given the transfer
  rates of the devices, it is possible to determine the average seek times
  for each device.

OPERANDS
  drive...
      Forces iostat to display specific drives.	 If drive is not specified,
      iostat displays the first four drives (even if more than four disk
      drives are configured in the system).

  interval
      Causes iostat to report once each interval seconds.  The first report
      is for all time since a reboot, and each subsequent report is for the
      last interval only.

  count
      Specifies the number of reports.	For example, iostat 1 10 would
      produce 10 reports at 1-second intervals.	 You cannot specify count
      without interval because the first numeric argument to iostat is
      assumed to be interval.

      If a disk drive is attached and configured but has never been accessed,
      iostat displays the disk name as dkn, where n is the drive number of
      the console name for the drive. For example, if dka500 is the console
      name of the never accessed disk, the name iostat uses is dk500.







EXAMPLES
  The output from this example displays cpu, terminal, and disk statistics
  for the first four disks on the system providing 5 reports in 1 second
  intervals.

       # iostat 1 5
	     tty     rz1      rz2      rz3	rz4	cpu
	tin tout bps tps  bps tps  bps tps  bps tps  us ni sy id
	  1   52   2   0    1	0   13	 1    4	  1   8	 0  9 83
	  1   16   7   1    2	0    5	 2    2	  0   3	 0 10 87
	  0    0   0   0    0	0    0	 0    0	  0   0	 0  1 98
	  2    2   2   1    0	0   50	 6    0	  0   9	 0  9 82
	  1  191   2   1    0	0   47	 6    0	  0   8	 0  9 83

  Note that this example does not show the average seek times (msps) for the
  disk drives.	Not all disk drives report seek time.

SEE ALSO
  Commands:  vmstat(1)