IOSTAT(8) BSD System Manager's Manual IOSTAT(8)NAME
iostat - report I/O statistics
SYNOPSIS
iostat [-c count] [-M core] [-N system] [-w wait] [drives]
DESCRIPTION
Iostat displays kernel I/O statistics on terminal, disk and cpu opera-
tions.
The options are as follows:
-c Repeat the display count times. The first display is for the time
since a reboot and each subsequent report is for the time period
since the last display. If no wait interval is specified, the de-
fault is 1 second.
-M Extract values associated with the name list from the specified
core instead of the default ``/dev/kmem''.
-N Extract the name list from the specified system instead of the de-
fault ``/bsd''.
-w Pause wait seconds between each display. If no repeat count is
specified, the default is infinity.
Iostat displays its information in the following format:
tty
tin characters read from terminals
tout characters written to terminals
disks
Disk operations (this field is system dependent). The header of
the field is the disk name and unit number. Iostat displays as
many drives as can fit on the screen, or all drives on the system
when stdout is not directed to a tty. To force iostat to display
specific drives, their names may be supplied on the command line.
sps sectors transferred per second
tps transfers per second
msps milliseconds per average seek (including implied seeks and
rotational latency)
cpu
usr % of cpu time in user mode
nic % of cpu time in user mode running niced processes
sys % of cpu time in system mode
int % of cpu time handling interrupts
idl % of cpu time in idle mode
ENVIRONMENT
The following environment variables affect the execution of iostat:
COLUMNS If this variable contains a string representing a decimal in-
teger, it is used as the column position width for displaying
multiple-text-column output. The iostat utility calculates
how many disk drives may be displayed based on the width pro-
vided.
FILES
/bsd Default kernel namelist.
/dev/kmem Default memory file.
SEE ALSOfstat(1), netstat(1), nfsstat(1), ps(1), systat(1), pstat(8), vm-
stat(8)
The sections starting with ``Interpreting system activity'' in Installing
and Operating 4.3BSD.
4th Berkeley Distribution June 6, 1993 2