1.\" $OpenBSD: iostat.8,v 1.17 2001/04/12 18:12:01 deraadt Exp $ 2.\" $NetBSD: iostat.8,v 1.10 1996/10/25 18:21:57 scottr Exp $ 3.\" 4.\" Copyright (c) 1985, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" from: @(#)iostat.8 8.1 (Berkeley) 6/6/93 36.\" 37.Dd January 18, 1996 38.Dt IOSTAT 8 39.Os 40.Sh NAME 41.Nm iostat 42.Nd report 43.Tn I/O 44statistics 45.Sh SYNOPSIS 46.Nm iostat 47.Op Fl CdDIT 48.Op Fl c Ar count 49.Op Fl M Ar core 50.Op Fl N Ar system 51.Op Fl w Ar wait 52.Op Ar drives 53.Sh DESCRIPTION 54.Nm iostat 55displays kernel 56.Tn I/O 57statistics on terminal, disk and CPU operations. 58By default, 59.Nm iostat 60displays one line of statistics averaged over the machine's run time. 61The use of 62.Fl c 63presents successive lines averaged over the 64.Ar wait 65period. 66The 67.Fl I 68option causes 69.Nm iostat 70to print raw, unaveraged values. 71.Pp 72The options are as follows: 73.Bl -tag -width Ds 74.It Fl c 75Repeat the display 76.Ar count 77times. 78Unless the 79.Fl I 80flag is in effect, the first display is for the time since a reboot and 81each subsequent report is for the time period since the last display. 82If no 83.Ar wait 84interval is specified, the default is 1 second. 85.It Fl C 86Show CPU statistics. 87This is enabled by default unless the 88.Fl d , 89.Fl D , 90or 91.Fl T 92flags are used. 93.It Fl d 94Show disk statistics. 95This is the default. 96Displays kilobytes per 97transfer, number of transfers, and megabytes transferred. 98Use of this flag disables display of CPU and tty statistics. 99.It Fl D 100Show alternate disk statistics. 101Displays kilobytes transferred, number of 102transfers, and time spent in transfers. 103Use of this flag disables the default display. 104.It Fl I 105Show the running total values, rather than an average. 106.It Fl M 107Extract values associated with the name list from the specified core 108instead of the default 109.Dq Pa /dev/mem . 110.It Fl N 111Extract the name list from the specified system instead of the default 112.Dq Pa /bsd . 113.It Fl T 114Show tty statistics. 115This is enabled by default unless the 116.Fl C , 117.Fl d , 118or 119.Fl D 120flags are used. 121.It Fl w 122Pause 123.Ar wait 124seconds between each display. 125If no repeat 126.Ar count 127is specified, the default is infinity. 128.El 129.Pp 130.Nm iostat 131displays its information in the following format: 132.Bl -tag -width flag 133.It tty 134.Bl -tag -width indent -compact 135.It tin 136characters read from terminals 137.It tout 138characters written to terminals 139.El 140.It disks 141Disk operations. 142The header of the field is the disk name and unit number. 143If more than four disk drives are configured in the system, 144.Nm iostat 145displays only the first four drives. 146To force 147.Nm iostat 148to display specific drives, their names may be supplied on the command 149line. 150.Pp 151.Bl -tag -width indent -compact 152.It KB/t 153Kilobytes transferred per disk transfer 154.It t/s 155transfers per second 156.It MB/s 157Megabytes transferred per second 158.Pp 159.El 160The alternate display format, (selected with 161.Fl D ) , 162presents the following values. 163.Bl -tag -width indent -compact 164.It KB 165Kilobytes transferred 166.It xfr 167Disk transfers 168.It time 169Seconds spent in disk activity 170.El 171.It cpu 172.Bl -tag -width indent -compact 173.It \&us 174% of CPU time in user mode 175.It \&ni 176% of CPU time in user mode running niced processes 177.It \&sy 178% of CPU time in system mode 179.It \&in 180% of CPU time processing interrupts 181.It \&id 182% of CPU time in idle mode 183.El 184.El 185.Sh FILES 186.Bl -tag -width /dev/mem -compact 187.It Pa /bsd 188default kernel namelist 189.It Pa /dev/mem 190default memory file 191.El 192.Sh SEE ALSO 193.Xr fstat 1 , 194.Xr netstat 1 , 195.Xr nfsstat 1 , 196.Xr \&ps 1 , 197.Xr systat 1 , 198.Xr pstat 8 , 199.Xr vmstat 8 200.Pp 201The sections starting with 202.Dq Interpreting system activity 203in 204.%T "Installing and Operating 4.3BSD" . 205