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BSD 2.11 - man page for iostat (bsd section 1)

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IOSTAT(1)										IOSTAT(1)

NAME
       iostat - report I/O statistics

SYNOPSIS
       iostat [ drives ] [ interval [ count ] ]

DESCRIPTION
       Iostat iteratively reports the number of characters read and written to terminals per sec-
       ond, and, for each disk, the number of transfers per  second,  kilobytes  transferred  per
       second,	and  the milliseconds per average seek.  It also gives the percentage of time the
       system has spent in user mode, in user mode running low	priority  (niced)  processes,  in
       system mode, and idling.

       To compute this information, for each disk, seeks and data transfer completions and number
       of words transferred are counted; for terminals collectively, the number of input and out-
       put  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.  From  these  numbers  and  given  the
       transfer  rates	of  the  devices  it is possible to determine 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.

       If more than 4 disk drives are configured in the system, iostat displays only the first	4
       drives, with priority given to Massbus disk drives (i.e. if both Unibus and Massbus drives
       are present and the total number of drives exceeds 4, then some number  of  Unibus  drives
       will  not  be  displayed in favor of the Massbus drives).  To force iostat to display spe-
       cific drives, their names may be supplied on the command line.

FILES
       /dev/kmem
       /vmunix

SEE ALSO
       vmstat(1)

4th Berkeley Distribution		  April 29, 1985				IOSTAT(1)
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