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iostat(1)							    iostat(1)



NAME

  iostat - Reports I/O statistics

SYNOPSIS

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

OPERANDS

  drive...
      Forces iostat to display specific	drives.	 If drive is not specified
      (or the specified	drive does not exist on	the system or cluster, iostat
      displays the first two drives (even if more than two disk	drives are
      configured in the	system).

  interval
      Causes iostat to report once each	interval seconds.  The first report
      is for all time since the	system was last	booted,	and each subsequent
      report is	for the	last interval only.The value must not be 0.

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

DESCRIPTION

  The iostat command reports the following information:

    +  For terminals (collectively), the number	of characters read and writ-
       ten per second.

    +  For each	disk, the number of transfers per second and bytes
       transferred per second (in kilobytes).

    +  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 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.

  When you issue an iostat command on a	cluster	member,	it displays statis-
  tics only for	those disks that are local to the member and that member's
  usage	of those shared	disks that it has mounted.   It	displays 0 for other
  disks	in the cluster (those it doesn't have mounted),	regardless of whether
  they are on the shared bus or	are local to some other	member.


EXAMPLES

  The output from this example displays	cpu, terminal, and disk	statistics
  for the first	two disks on the system	providing 5 reports at 1 second
  intervals:

       # iostat	1 5
	   tty	    floppy1	     dsk9	   cpu
	tin tout    bps	   tps	  bps	 tps  us ni sy id
	  0    3      0	     0	    0	   0   1  0  4 95
	  4   58      0	     0	    0	   0   1  0  2 97
	  1   53      0	     0	    0	   0   0  0  2 98
	  5   59      0	     0	    0	   0   1  0  1 98
	  6   60      0	     0	    0	   0   1  0  2 97

  The second example specifies device names in the command:

       # iostat	dsk2 dsk3 cdrom2
	      tty	dsk2	cdrom2	     dsk3	  cpu
	tin   tout  bps	 tps  bps  tps	 bps  tps  us  ni  sy  id
	  0    13    11	  5    5    2	2427 1213   0	1   1  98

SEE ALSO

  Commands:  vmstat(1)