1.\" $OpenBSD: iostat.8,v 1.28 2022/09/17 11:39:09 jmc 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. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" from: @(#)iostat.8 8.1 (Berkeley) 6/6/93 32.\" 33.Dd $Mdocdate: September 17 2022 $ 34.Dt IOSTAT 8 35.Os 36.Sh NAME 37.Nm iostat 38.Nd report I/O statistics 39.Sh SYNOPSIS 40.Nm iostat 41.Op Fl CDdIT 42.Op Fl c Ar count 43.Op Fl M Ar core 44.Op Fl N Ar system 45.Op Fl w Ar wait 46.Op Ar drives 47.Sh DESCRIPTION 48.Nm 49displays kernel I/O statistics on terminal, disk and CPU operations. 50By default, 51.Nm 52displays one line of statistics averaged over the machine's run time. 53The 54.Fl I 55option causes 56.Nm iostat 57to print raw, unaveraged values. 58.Pp 59The options are as follows: 60.Bl -tag -width Ds 61.It Fl C 62Show CPU statistics. 63This is enabled by default unless the 64.Fl D , 65.Fl d , 66or 67.Fl T 68flags are used. 69.It Fl c Ar count 70Repeat the display 71.Ar count 72times. 73Unless the 74.Fl I 75flag is in effect, the first display is for the time since a reboot and 76each subsequent report is for the time period since the last display. 77Unless overridden by the 78.Fl w 79option, the wait interval between lines is 1 second. 80.It Fl D 81Show alternate disk statistics. 82Displays kilobytes transferred, number of 83transfers, and time spent in transfers. 84Use of this flag disables the default display. 85.It Fl d 86Show disk statistics. 87This is the default. 88Displays kilobytes per 89transfer, number of transfers, and megabytes transferred. 90Use of this flag disables display of CPU and tty statistics. 91.It Fl I 92Show the running total values, rather than an average. 93.It Fl M Ar core 94Extract values associated with the name list from the specified 95.Ar core 96instead of the default 97.Pa /dev/mem . 98.It Fl N Ar system 99Extract the name list from the specified 100.Ar system 101instead of the default 102.Dq Pa /bsd . 103.It Fl T 104Show tty statistics. 105This is enabled by default unless the 106.Fl C , 107.Fl D , 108or 109.Fl d 110flags are used. 111.It Fl w Ar wait 112Pause 113.Ar wait 114seconds between each display. 115Unless a 116.Ar count 117is specified via the 118.Fl c 119option, 120.Nm 121will display output until it is interrupted. 122.El 123.Pp 124.Nm 125displays its information in the following format: 126.Bl -tag -width flag 127.It tty 128.Bl -tag -width indent -compact 129.It tin 130characters read from terminals 131.It tout 132characters written to terminals 133.El 134.It disks 135Disk operations. 136The header of the field is the disk name and unit number. 137If more than four disk drives are configured in the system, 138.Nm 139displays only the first four drives. 140To force 141.Nm 142to display specific drives, their names may be supplied on the command 143line. 144.Pp 145.Bl -tag -width indent -compact 146.It KB/t 147Kilobytes transferred per disk transfer 148.It t/s 149Transfers per second 150.It MB/s 151Megabytes transferred per second 152.El 153.Pp 154The alternate display format, selected with 155.Fl D , 156presents the following values: 157.Pp 158.Bl -tag -width indent -compact 159.It KB 160Kilobytes transferred 161.It xfr 162Disk transfers 163.It time 164Seconds spent in disk activity 165.El 166.It cpu 167.Bl -tag -width indent -compact 168.It \&us 169% of CPU time in user mode 170.It \&ni 171% of CPU time in user mode running niced processes 172.It \&sy 173% of CPU time in system mode 174.It \&sp 175% of CPU time spent spinning 176.It \&in 177% of CPU time processing interrupts 178.It \&id 179% of CPU time in idle mode 180.El 181.El 182.Sh FILES 183.Bl -tag -width /dev/mem -compact 184.It Pa /bsd 185default kernel namelist 186.It Pa /dev/mem 187default memory file 188.El 189.Sh SEE ALSO 190.Xr fstat 1 , 191.Xr netstat 1 , 192.Xr nfsstat 1 , 193.Xr ps 1 , 194.Xr systat 1 , 195.Xr top 1 , 196.Xr pstat 8 , 197.Xr vmstat 8 198.Pp 199The sections starting with 200.Dq Interpreting system activity 201in 202.%T "Installing and Operating 4.3BSD" . 203