.\"
.\" Copyright (c) 1997 Kenneth D. Merry.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. The name of the author may not be used to endorse or promote products
.\"    derived from this software without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD: src/usr.sbin/iostat/iostat.8,v 1.11.2.9 2002/12/29 16:35:41 schweikh Exp $
.\" $DragonFly: src/usr.sbin/iostat/iostat.8,v 1.3 2004/12/22 11:01:49 joerg Exp $
.\"
.\" Copyright (c) 1985, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"	@(#)iostat.8	8.1 (Berkeley) 6/6/93
.\"
.Dd December 22, 1997
.Dt IOSTAT 8
.Os
.Sh NAME
.Nm iostat
.Nd report
.Tn I/O
statistics
.Sh SYNOPSIS
.Nm
.Op Fl CdhKIoT?\&
.Op Fl c Ar count
.Op Fl n Ar devs
.Oo
.Fl t
.Sm off
.Ar type , if , pass
.Sm on
.Oc
.Op Fl w Ar wait
.Op Ar drives
.Sh DESCRIPTION
.Nm Iostat
displays kernel
.Tn I/O
statistics on terminal, device and cpu
operations.
.Pp
The options are as follows:
.Bl -tag -width flag
.It Fl c
Repeat the display
.Ar count
times.
If no
.Ar wait
interval is specified, the default is 1 second.
.It Fl C
Display CPU statistics.
This is on by default, unless
.Fl d
is specified.
.It Fl d
Display only device statistics.
If this flag is turned on, only device statistics will be displayed, unless
.Fl C
or
.Fl T
is also specified to enable the display of CPU or TTY statistics.
.It Fl h
Put
.Nm
in
.Sq top
mode.
In this mode,
.Nm
will show devices in order from highest to lowest bytes
per measurement cycle.
.It Fl I
Display total statistics for a given time period, rather than average
statistics for each second during that time period.
.It Fl K
In the blocks transferred display (-o), display block count in kilobytes rather
then the device native block size.
.It Fl n
Display up to
.Ar devs
number of devices.
.Nm
will display fewer devices if there aren't
.Ar devs
devices present.
.It Fl o
Display old-style
.Nm
device statistics.
Sectors per second, transfers per second, and milliseconds per seek are
displayed.
If
.Fl I
is specified, total blocks/sectors, total transfers, and
milliseconds per seek are displayed.
.It Fl t
Specify which types of devices to display.
There are three different categories of devices:
.Pp
.Bl -tag -width indent -compact
.It device type:
.Bl -tag -width 9n -compact
.It da
Direct Access devices
.It sa
Sequential Access devices
.It printer
Printers
.It proc
Processor devices
.It worm
Write Once Read Multiple devices
.It cd
CD devices
.It scanner
Scanner devices
.It optical
Optical Memory devices
.It changer
Medium Changer devices
.It comm
Communication devices
.It array
Storage Array devices
.It enclosure
Enclosure Services devices
.It floppy
Floppy devices
.El
.Pp
.It interface:
.Bl -tag -width 9n -compact
.It IDE
Integrated Drive Electronics devices
.It SCSI
Small Computer System Interface devices
.It other
Any other device interface
.El
.Pp
.It passthrough:
.Bl -tag -width 9n -compact
.It pass
Passthrough devices
.El
.El
.Pp
The user must specify at least one device type, and may specify at most
one device type from each category.
Multiple device types in a single device type statement must be separated by
commas.
.Pp
Any number of
.Fl t
arguments may be specified on the command line.
All
.Fl t
arguments are ORed together to form a matching expression against which
all devices in the system are compared.
Any device that fully matches any
.Fl t
argument will be included in the
.Nm
output, up to the number of devices that can be displayed in
80 columns, or the maximum number of devices specified by the user.
.It Fl T
Display TTY statistics.
This is on by default, unless
.Fl d
is specified.
.It Fl w
Pause
.Ar wait
seconds between each display.
If no repeat
.Ar count
is specified, the default is infinity.
.It Fl ?\&
Display a usage statement and exit.
.El
.Pp
.Nm Iostat
displays its information in the following format:
.Bl -tag -width flag
.It tty
.Bl -tag -width indent -compact
.It tin
characters read from terminals
.It tout
characters written to terminals
.El
.It devices
Device operations.
The header of the field is the device name and unit number.
.Nm
will display as many devices as will fit in a standard 80 column screen, or
the maximum number of devices in the system, whichever is smaller.
If
.Fl n
is specified on the command line,
.Nm
will display the smaller of the
requested number of devices, and the maximum number of devices in the system.
To force
.Nm
to display specific drives, their names may be supplied on the command
line.
.Nm
will not display more devices than will fit in an 80 column screen, unless
the
.Fl n
argument is given on the command line to specify a maximum number of
devices to display.
If fewer devices are specified on the command line than will fit in an 80
column screen,
.Nm
will show only the specified devices.
.Pp
The standard
.Nm
device display shows the following statistics:
.Pp
.Bl -tag -width indent -compact
.It KB/t
kilobytes per transfer
.It tps
transfers per second
.It MB/s
megabytes per second
.El
.Pp
The standard
.Nm
device display, with the
.Fl I
flag specified, shows the following statistics:
.Pp
.Bl -tag -width indent -compact
.It KB/t
kilobytes per transfer
.It xfrs
total number of transfers
.It MB
total number of megabytes transferred
.El
.Pp
The old-style
.Nm
display (using
.Fl o )
shows the following statistics:
.Pp
.Bl -tag -width indent -compact
.It sps
sectors transferred per second
.It tps
transfers per second
.It msps
average milliseconds per transaction
.El
.Pp
The old-style
.Nm
display, with the
.Fl I
flag specified, shows the following statistics:
.Pp
.Bl -tag -width indent -compact
.It blk
total blocks/sectors transferred
.It xfr
total transfers
.It msps
average milliseconds per transaction
.El
.It cpu
.Bl -tag -width indent -compact
.It \&us
% of cpu time in user mode
.It \&ni
% of cpu time in user mode running niced processes
.It \&sy
% of cpu time in system mode
.It \&in
% of cpu time in interrupt mode
.It \&id
% of cpu time in idle mode
.El
.El
.Sh EXAMPLES
.Dl iostat -w 1 da0 da1 cd0
.Pp
Display statistics for the first two Direct Access devices and the first
CDROM device every second ad infinitum.
.Pp
.Dl iostat -c 2
.Pp
Display the statistics for the first four devices in the system twice, with
a one second display interval.
.Pp
.Dl iostat -t da -t cd -w 1
.Pp
Display statistics for all CDROM and Direct Access devices every second
ad infinitum.
.Pp
.Dl iostat -t da,scsi,pass -t cd,scsi,pass
.Pp
Display statistics once for all SCSI passthrough devices that provide access
to either Direct Access or CDROM devices.
.Pp
.Dl iostat -h -n 8 -w 1
.Pp
Display up to 8 devices with the most I/O every second ad infinitum.
.Pp
.Dl iostat -dh -t da -w 1
.Pp
Omit the TTY and CPU displays, show devices in order of performance and
show only Direct Access devices every second ad infinitum.
.Pp
.Dl iostat -Iw 3
.Pp
Display total statistics every three seconds ad infinitum.
.Pp
.Dl iostat -odICTw 2 -c 9
.Pp
Display total statistics using the old-style output format 9 times, with
a two second interval between each measurement/display.
The
.Fl d
flag generally disables the TTY and CPU displays, but since the
.Fl T
and
.Fl C
flags are given, the TTY and CPU displays will be displayed.
.Sh SEE ALSO
.Xr fstat 1 ,
.Xr netstat 1 ,
.Xr nfsstat 1 ,
.Xr ps 1 ,
.Xr systat 1 ,
.Xr pstat 8 ,
.Xr vmstat 8
.Pp
The sections starting with ``Interpreting system activity'' in
.%T "Installing and Operating 4.3BSD" .
.Sh HISTORY
This version of
.Nm
first appeared in
.Fx 3.0 .
.Sh AUTHORS
.An Kenneth Merry Aq ken@FreeBSD.org