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.\" $FreeBSD$ 29.\" 30.\" Copyright (c) 1985, 1991, 1993 31.\" The Regents of the University of California. All rights reserved. 32.\" 33.\" Redistribution and use in source and binary forms, with or without 34.\" modification, are permitted provided that the following conditions 35.\" are met: 36.\" 1. Redistributions of source code must retain the above copyright 37.\" notice, this list of conditions and the following disclaimer. 38.\" 2. Redistributions in binary form must reproduce the above copyright 39.\" notice, this list of conditions and the following disclaimer in the 40.\" documentation and/or other materials provided with the distribution. 41.\" 3. All advertising materials mentioning features or use of this software 42.\" must display the following acknowledgement: 43.\" This product includes software developed by the University of 44.\" California, Berkeley and its contributors. 45.\" 4. Neither the name of the University nor the names of its contributors 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 December 22, 1997 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 73.Op Fl CdhKIoT?\& 74.Op Fl c Ar count 75.Op Fl M Ar core 76.Op Fl n Ar devs 77.Op Fl N Ar system 78.Oo 79.Fl t 80.Sm off 81.Ar type , if , pass 82.Sm on 83.Oc 84.Op Fl w Ar wait 85.Op Ar drives 86.Sh DESCRIPTION 87.Nm Iostat 88displays kernel 89.Tn I/O 90statistics on terminal, device and cpu operations. 91The first statistics that are printed are averaged over the system uptime. 92To get information about the current activity, a suitable wait time should 93be specified, so that the subsequent sets of printed statistics will be 94averaged over that time. 95.Pp 96.Pp 97The options are as follows: 98.Bl -tag -width flag 99.It Fl c 100Repeat the display 101.Ar count 102times. 103If no 104.Ar wait 105interval is specified, the default is 1 second. 106.It Fl C 107Display CPU statistics. 108This is on by default, unless 109.Fl d 110is specified. 111.It Fl d 112Display only device statistics. 113If this flag is turned on, only device statistics will be displayed, unless 114.Fl C 115or 116.Fl T 117is also specfied to enable the display of CPU or TTY statistics. 118.It Fl h 119Put iostat in 120.Sq top 121mode. 122In this mode, iostat will show devices in order from highest to lowest bytes 123per measurement cycle. 124.It Fl I 125Display total statstics for a given time period, rather than average 126statistics for each second during that time period. 127.It Fl K 128In the blocks transfered display (-o), display block count in kilobytes rather 129then the device native block size. 130.It Fl M 131Extract values associated with the name list from the specified core 132instead of the default 133.Dq Pa /dev/kmem . 134.It Fl n 135Display up to 136.Ar devs 137number of devices. 138.Nm 139will display fewer devices if there aren't 140.Ar devs 141devices present. 142.It Fl N 143Extract the name list from the specified system instead of the default 144.Dq Pa /kernel . 145.It Fl o 146Display old-style 147.Nm 148device statistics. 149Sectors per second, transfers per second, and miliseconds per seek are 150displayed. 151If 152.Fl I 153is specified, total blocks/sectors, total transfers, and 154miliseconds per seek are displayed. 155.It Fl t 156Specify which types of devices to display. 157There are three different categories of devices: 158.Pp 159.Bl -tag -width indent -compact 160.It device type: 161.Bl -tag -width 9n -compact 162.It da 163Direct Access devices 164.It sa 165Sequential Access devices 166.It printer 167Printers 168.It proc 169Processor devices 170.It worm 171Write Once Read Multiple devices 172.It cd 173CD devices 174.It scanner 175Scanner devices 176.It optical 177Optical Memory devices 178.It changer 179Medium Changer devices 180.It comm 181Communication devices 182.It array 183Storage Array devices 184.It enclosure 185Enclosure Services devices 186.It floppy 187Floppy devices 188.El 189.Pp 190.It interface: 191.Bl -tag -width 9n -compact 192.It IDE 193Integrated Drive Electronics devices 194.It SCSI 195Small Computer System Interface devices 196.It other 197Any other device interface 198.El 199.Pp 200.It passthrough: 201.Bl -tag -width 9n -compact 202.It pass 203Passthrough devices 204.El 205.El 206.Pp 207The user must specify at least one device type, and may specify at most 208one device type from each category. 209Multiple device types in a single device type statement must be separated by 210commas. 211.Pp 212Any number of 213.Fl t 214arguments may be specified on the command line. 215All 216.Fl t 217arguments are ORed together to form a matching expression against which 218all devices in the system are compared. 219Any device that fully matches any 220.Fl t 221argument will be included in the 222.Nm 223output, up to the number of devices that can be displayed in 22480 columns, or the maximum number of devices specified by the user. 225.It Fl T 226Display TTY statistics. 227This is on by default, unless 228.Fl d 229is specified. 230.It Fl w 231Pause 232.Ar wait 233seconds between each display. 234If no repeat 235.Ar count 236is specified, the default is infinity. 237.It Fl ?\& 238Display a usage statement and exit. 239.El 240.Pp 241.Nm Iostat 242displays its information in the following format: 243.Bl -tag -width flag 244.It tty 245.Bl -tag -width indent -compact 246.It tin 247characters read from terminals 248.It tout 249characters written to terminals 250.El 251.It devices 252Device operations. 253The header of the field is the device name and unit number. 254.Nm 255will display as many devices as will fit in a standard 80 column screen, or 256the maximum number of devices in the system, whichever is smaller. 257If 258.Fl n 259is specified on the command line, iostat will display the smaller of the 260requested number of devices, and the maximum number of devices in the system. 261To force 262.Nm 263to display specific drives, their names may be supplied on the command 264line. 265.Nm 266will not display more devices than will fit in an 80 column screen, unless 267the 268.Fl n 269argument is given on the command line to specify a maximum number of 270devices to display. 271If fewer devices are specified on the command line than will fit in an 80 272column screen, iostat will show only the specified devices. 273.Pp 274The standard 275.Nm 276device display shows the following statistics: 277.Pp 278.Bl -tag -width indent -compact 279.It KB/t 280kilobytes per transfer 281.It tps 282transfers per second 283.It MB/s 284megabytes per second 285.El 286.Pp 287The standard 288.Nm 289device display, with the 290.Fl I 291flag specified, shows the following statistics: 292.Pp 293.Bl -tag -width indent -compact 294.It KB/t 295kilobytes per transfer 296.It xfrs 297total number of transfers 298.It MB 299total number of megabytes transferred 300.El 301.Pp 302The old-style 303.Nm 304display (using 305.Fl o ) 306shows the following statistics: 307.Pp 308.Bl -tag -width indent -compact 309.It sps 310sectors transferred per second 311.It tps 312transfers per second 313.It msps 314average milliseconds per transaction 315.El 316.Pp 317The old-style 318.Nm 319display, with the 320.Fl I 321flag specified, shows the following statistics: 322.Pp 323.Bl -tag -width indent -compact 324.It blk 325total blocks/sectors transferred 326.It xfr 327total transfers 328.It msps 329average milliseconds per transaction 330.El 331.It cpu 332.Bl -tag -width indent -compact 333.It \&us 334% of cpu time in user mode 335.It \&ni 336% of cpu time in user mode running niced processes 337.It \&sy 338% of cpu time in system mode 339.It \&in 340% of cpu time in interrupt mode 341.It \&id 342% of cpu time in idle mode 343.El 344.El 345.Sh FILES 346.Bl -tag -width /dev/kmem -compact 347.It Pa /kernel 348Default kernel namelist. 349.It Pa /dev/kmem 350Default memory file. 351.El 352.Sh EXAMPLES 353.Dl iostat -w 1 da0 da1 cd0 354.Pp 355Display statistics for the first two Direct Access devices and the first 356CDROM device every second ad infinitum. 357.Pp 358.Dl iostat -c 2 359.Pp 360Display the statistics for the first four devices in the system twice, with 361a one second display interval. 362.Pp 363.Dl iostat -t da -t cd -w 1 364.Pp 365Display statistics for all CDROM and Direct Access devices every second 366ad infinitum. 367.Pp 368.Dl iostat -t da,scsi,pass -t cd,scsi,pass 369.Pp 370Display statistics once for all SCSI passthrough devices that provide access 371to either Direct Access or CDROM devices. 372.Pp 373.Dl iostat -h -n 8 -w 1 374.Pp 375Display up to 8 devices with the most I/O every second ad infinitum. 376.Pp 377.Dl iostat -dh -t da -w 1 378.Pp 379Omit the TTY and CPU displays, show devices in order of performance and 380show only Direct Access devices every second ad infinitum. 381.Pp 382.Dl iostat -Iw 3 383.Pp 384Display total statistics every three seconds ad infinitum. 385.Pp 386.Dl iostat -odICTw 2 -c 9 387.Pp 388Display total statistics using the old-style output format 9 times, with 389a two second interval between each measurement/display. 390The 391.Fl d 392flag generally disables the TTY and CPU displays, but since the 393.Fl T 394and 395.Fl C 396flags are given, the TTY and CPU displays will be displayed. 397.Sh SEE ALSO 398.Xr fstat 1 , 399.Xr netstat 1 , 400.Xr nfsstat 1 , 401.Xr ps 1 , 402.Xr systat 1 , 403.Xr pstat 8 , 404.Xr vmstat 8 405.Pp 406The sections starting with ``Interpreting system activity'' in 407.%T "Installing and Operating 4.3BSD" . 408.Sh HISTORY 409This version of 410.Nm 411first appeared in 412.Fx 3.0 . 413.Sh BUGS 414The use of 415.Nm 416as a debugging tool for crash dumps is probably limited because there is 417currently no way to get statistics that only cover the time immediately before 418the crash. 419.Sh AUTHORS 420.An Kenneth Merry Aq ken@FreeBSD.org 421