IOSTAT(1)						      General Commands Manual							 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 second, 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 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.	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 specific 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)