IOSTAT(1M)					       IOSTAT(1M)

NAME
       iostat - report I/O statistics

SYNOPSIS
       iostat [ option ] ...  [ interval [ count ] ]

DESCRIPTION
       Iostat  delves into the system and reports certain statis-
       tics kept about	input-output  activity.	  Information  is
       kept  about  up	to three different disks (RF, RK, RP) and
       about typewriters.  For each disk, IO completions and num-
       ber of words transferred are counted; for typewriters col-
       lectively, the number of input and output  characters  are
       counted.	  Also,	 each  sixtieth of a second, the state of
       each disk is examined and a tally is made if the	 disk  is
       active.	 The  tally  goes  into	 one  of four categories,
       depending on whether the system is executing in user mode,
       in `nice' (background) user mode, in system mode, or idle.
       From all these numbers and from the known  transfer  rates
       of  the	devices	 it  is possible to determine information
       such as the degree of IO overlap and  average  seek  times
       for each device.

       The  optional  interval	argument  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.

       The  optional  count  argument  restricts  the  number  of
       reports.

       With  no	 option argument iostat reports for each disk the
       number of transfers per minute, the milliseconds per aver-
       age seek, and the milliseconds per data transfer exclusive
       of seek time.  It also gives the percentage  of	time  the
       system  has spend in each of the four categories mentioned
       above.

       The following options are available:

       -t     Report the number of characters of terminal IO  per
	      second as well.

       -i     Report  the percentage of time spend in each of the
	      four categories mentioned above, the percentage  of
	      time  each  disk	was  active (seeking or transfer-
	      ring), the percentage of time any disk was  active,
	      and  the	percentage  of	time  spent in `IO wait:'
	      idle, but with a disk active.

       -s     Report the raw timing information: 32 numbers indi-
	      cating  the percentage of time spent in each of the
	      possible configurations of 4 system states and 8 IO
	      states (3 disks each active or not).

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IOSTAT(1M)					       IOSTAT(1M)

       -b     Report on the usage of IO buffers.

FILES
       /dev/mem, /unix

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