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.

Iostat displays the first 4 drives. To force iostat to display
specific drives, their names may be supplied on the command line.

FILES
/dev/kmem
/vmunix