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1.\"
2.\" Copyright (c) 1997 Kenneth D. Merry.
3.\" All rights reserved.
4.\"
5.\" Redistribution and use in source and binary forms, with or without
6.\" modification, are permitted provided that the following conditions
7.\" are met:
8.\" 1. Redistributions of source code must retain the above copyright
9.\" notice, this list of conditions and the following disclaimer.
10.\" 2. Redistributions in binary form must reproduce the above copyright
11.\" notice, this list of conditions and the following disclaimer in the
12.\" documentation and/or other materials provided with the distribution.
13.\" 3. The name of the author may not be used to endorse or promote products
14.\" derived from this software without specific prior written permission.
15.\"
16.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26.\" SUCH DAMAGE.
27.\"
28.\" $FreeBSD: src/usr.sbin/iostat/iostat.8,v 1.20 2001/08/07 13:59:48 ru Exp $
29.\"
30.\" Copyright (c) 1985, 1991, 1993
31.\" The Regents of the University of California. All rights reserved.
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34.\" modification, are permitted provided that the following conditions
35.\" are met:
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40.\" documentation and/or other materials provided with the distribution.
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43.\" This product includes software developed by the University of
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46.\" may be used to endorse or promote products derived from this software
47.\" without specific prior written permission.
48.\"
49.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
50.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
51.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
52.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
53.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
54.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
55.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
56.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
57.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
58.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
59.\" SUCH DAMAGE.
60.\"
61.\" @(#)iostat.8 8.1 (Berkeley) 6/6/93
62.\"
63.Dd September 27, 2001
64.Dt IOSTAT 8
65.Os
66.Sh NAME
67.Nm iostat
68.Nd report
69.Tn I/O
70statistics
71.Sh SYNOPSIS
72.Nm iostat
73.Op Fl CUdKIoT?\&
74.Op Fl c Ar count
75.Op Fl n Ar devs
76.Op Fl w Ar wait
77.Op Ar drives
78.Sh DESCRIPTION
79.Nm Iostat
80displays kernel
81.Tn I/O
82statistics on terminal, device and cpu operations.
83The first statistics that are printed are averaged over the system uptime.
84To get information about the current activity, a suitable wait time should
85be specified, so that the subsequent sets of printed statistics will be
86averaged over that time.
87.Pp
88The options are as follows:
89.Bl -tag -width flag
90.\" ==========
91.It Fl ?\&
92Display a usage statement and exit.
93.\" ==========
94.It Fl C
95Display CPU statistics.
96This is on by default, unless
97.Fl d
98is specified.
99.\" ==========
100.It Fl c
101Repeat the display
102.Ar count
103times.
104If no
105.Ar wait
106interval is specified, the default is 1 second.
107.\" ==========
108.It Fl d
109Display only device statistics.
110If this flag is turned on, only device statistics will be displayed, unless
111.Fl C
112or
113.Fl U
114or
115.Fl T
116is also specfied to enable the display of CPU, load average or TTY statistics.
117.\" ==========
118.It Fl I
119Display total statstics for a given time period, rather than average
120statistics for each second during that time period.
121.\" ==========
122.It Fl K
123In the blocks transferred display (-o), display block count in kilobytes rather
124then the device native block size.
125.\" ==========
126.It Fl n
127Display up to
128.Ar devs
129number of devices.
130.Nm iostat
131will display fewer devices if there aren't
132.Ar devs
133devices present.
134.\" ==========
135.It Fl o
136Display old-style
137.Nm iostat
138device statistics.
139Sectors per second, transfers per second, and miliseconds per seek are
140displayed.
141If
142.Fl I
143is specified, total blocks/sectors, total transfers, and
144miliseconds per seek are displayed.
145.\" ==========
146.It Fl T
147Display TTY statistics.
148This is on by default, unless
149.Fl d
150is specified.
151.\" ==========
152.It Fl U
153Display system load averages.
154This is on by default, unless
155.Fl d
156is specified.
157.\" ==========
158.It Fl w
159Pause
160.Ar wait
161seconds between each display.
162If no repeat
163.Ar count
164is specified, the default is infinity.
165.El
166.Pp
167.Nm Iostat
168displays its information in the following format:
169.Bl -tag -width flag
170.It tty
171.Bl -tag -width indent -compact
172.It tin
173characters read from terminals
174.It tout
175characters written to terminals
176.El
177.It devices
178Device operations.
179The header of the field is the device name and unit number.
180.Nm iostat
181will display as many devices as will fit in a standard 80 column screen, or
182the maximum number of devices in the system, whichever is smaller.
183If
184.Fl n
185is specified on the command line,
186.Nm iostat
187will display the smaller of the
188requested number of devices, and the maximum number of devices in the system.
189To force
190.Nm iostat
191to display specific drives, their names may be supplied on the command
192line.
193.Nm iostat
194will not display more devices than will fit in an 80 column screen, unless
195the
196.Fl n
197argument is given on the command line to specify a maximum number of
198devices to display, or the list of specified devices exceeds 80 columns.
199If fewer devices are specified on the command line than will fit in an 80
200column screen,
201.Nm iostat
202will show only the specified devices.
203.Pp
204The standard
205.Nm iostat
206device display shows the following statistics:
207.Pp
208.Bl -tag -width indent -compact
209.It KB/t
210kilobytes per transfer
211.It tps
212transfers per second
213.It MB/s
214megabytes per second
215.El
216.Pp
217The standard
218.Nm iostat
219device display, with the
220.Fl I
221flag specified, shows the following statistics:
222.Pp
223.Bl -tag -width indent -compact
224.It KB/t
225kilobytes per transfer
226.It xfrs
227total number of transfers
228.It MB
229total number of megabytes transferred
230.El
231.Pp
232The old-style
233.Nm iostat
234display (using
235.Fl o )
236shows the following statistics:
237.Pp
238.Bl -tag -width indent -compact
239.It sps
240sectors transferred per second
241.It tps
242transfers per second
243.It msps
244average milliseconds per transaction
245.El
246.Pp
247The old-style
248.Nm iostat
249display, with the
250.Fl I
251flag specified, shows the following statistics:
252.Pp
253.Bl -tag -width indent -compact
254.It blk
255total blocks/sectors transferred
256.It xfr
257total transfers
258.It msps
259average milliseconds per transaction
260.El
261.It cpu
262.Bl -tag -width indent -compact
263.It \&us
264% of cpu time in user mode
265.It \&sy
266% of cpu time in system mode
267.It \&id
268% of cpu time in idle mode
269.El
270.El
271.Sh EXAMPLES
272.Dl iostat -w 1 disk0 disk2
273.Pp
274Display statistics for the first and third disk devices device every
275second ad infinitum.
276.Pp
277.Dl iostat -c 2
278.Pp
279Display the statistics for the first four devices in the system twice, with
280a one second display interval.
281.Pp
282.Dl iostat -Iw 3
283.Pp
284Display total statistics every three seconds ad infinitum.
285.Pp
286.Dl iostat -odICTw 2 -c 9
287.Pp
288Display total statistics using the old-style output format 9 times, with
289a two second interval between each measurement/display.
290The
291.Fl d
292flag generally disables the TTY and CPU displays, but since the
293.Fl T
294and
295.Fl C
296flags are given, the TTY and CPU displays will be displayed.
297.Sh SEE ALSO
298.Xr fstat 1 ,
299.Xr netstat 1 ,
300.Xr nfsstat 1 ,
301.Xr ps 1 ,
302.Xr pstat 8
303.Pp
304The sections starting with ``Interpreting system activity'' in
305.%T "Installing and Operating 4.3BSD" .
306.Sh HISTORY
307This version of
308.Nm iostat
309first appeared in
310.Nm FreeBSD 3.0 .
mirror of system_cmds