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 April 17, 2006 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 CdhIKoTxz?\& 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 87The 88.Nm 89utility displays kernel 90.Tn I/O 91statistics on terminal, device and cpu operations. 92The first statistics that are printed are averaged over the system uptime. 93To get information about the current activity, a suitable wait time should 94be specified, so that the subsequent sets of printed statistics will be 95averaged over that time. 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 specified to enable the display of CPU or TTY statistics. 118.It Fl h 119Put 120.Nm 121in 122.Sq top 123mode. 124In this mode, 125.Nm 126will show devices in order from highest to lowest bytes 127per measurement cycle. 128.It Fl I 129Display total statistics for a given time period, rather than average 130statistics for each second during that time period. 131.It Fl K 132In the blocks transferred display (-o), display block count in kilobytes rather 133then the device native block size. 134.It Fl M 135Extract values associated with the name list from the specified core 136instead of the default 137.Dq Pa /dev/kmem . 138.It Fl n 139Display up to 140.Ar devs 141number of devices. 142The 143.Nm 144utility will display fewer devices if there are not 145.Ar devs 146devices present. 147.It Fl N 148Extract the name list from the specified system instead of the default 149.Dq Pa /boot/kernel/kernel . 150.It Fl o 151Display old-style 152.Nm 153device statistics. 154Sectors per second, transfers per second, and milliseconds per seek are 155displayed. 156If 157.Fl I 158is specified, total blocks/sectors, total transfers, and 159milliseconds per seek are displayed. 160.It Fl t 161Specify which types of devices to display. 162There are three different categories of devices: 163.Pp 164.Bl -tag -width indent -compact 165.It device type: 166.Bl -tag -width 9n -compact 167.It da 168Direct Access devices 169.It sa 170Sequential Access devices 171.It printer 172Printers 173.It proc 174Processor devices 175.It worm 176Write Once Read Multiple devices 177.It cd 178CD devices 179.It scanner 180Scanner devices 181.It optical 182Optical Memory devices 183.It changer 184Medium Changer devices 185.It comm 186Communication devices 187.It array 188Storage Array devices 189.It enclosure 190Enclosure Services devices 191.It floppy 192Floppy devices 193.El 194.Pp 195.It interface: 196.Bl -tag -width 9n -compact 197.It IDE 198Integrated Drive Electronics devices 199.It SCSI 200Small Computer System Interface devices 201.It other 202Any other device interface 203.El 204.Pp 205.It passthrough: 206.Bl -tag -width 9n -compact 207.It pass 208Passthrough devices 209.El 210.El 211.Pp 212The user must specify at least one device type, and may specify at most 213one device type from each category. 214Multiple device types in a single device type statement must be separated by 215commas. 216.Pp 217Any number of 218.Fl t 219arguments may be specified on the command line. 220All 221.Fl t 222arguments are ORed together to form a matching expression against which 223all devices in the system are compared. 224Any device that fully matches any 225.Fl t 226argument will be included in the 227.Nm 228output, up to the number of devices that can be displayed in 22980 columns, or the maximum number of devices specified by the user. 230.It Fl T 231Display TTY statistics. 232This is on by default, unless 233.Fl d 234is specified. 235.It Fl w 236Pause 237.Ar wait 238seconds between each display. 239If no repeat 240.Ar count 241is specified, the default is infinity. 242.It Fl x 243Show extended disk statistics. 244Each disk is displayed on a line of its own with all available statistics. 245.It Fl z 246If 247.Fl x 248is specified, omit lines for devices with no activity. 249.It Fl ?\& 250Display a usage statement and exit. 251.El 252.Pp 253The 254.Nm 255utility displays its information in the following format: 256.Bl -tag -width flag 257.It tty 258.Bl -tag -width indent -compact 259.It tin 260characters read from terminals 261.It tout 262characters written to terminals 263.El 264.It devices 265Device operations. 266The header of the field is the device name and unit number. 267The 268.Nm 269utility 270will display as many devices as will fit in a standard 80 column screen, or 271the maximum number of devices in the system, whichever is smaller. 272If 273.Fl n 274is specified on the command line, 275.Nm 276will display the smaller of the 277requested number of devices, and the maximum number of devices in the system. 278To force 279.Nm 280to display specific drives, their names may be supplied on the command 281line. 282The 283.Nm 284utility 285will not display more devices than will fit in an 80 column screen, unless 286the 287.Fl n 288argument is given on the command line to specify a maximum number of 289devices to display. 290If fewer devices are specified on the command line than will fit in an 80 291column screen, 292.Nm 293will show only the specified devices. 294.Pp 295The standard 296.Nm 297device display shows the following statistics: 298.Pp 299.Bl -tag -width indent -compact 300.It KB/t 301kilobytes per transfer 302.It tps 303transfers per second 304.It MB/s 305megabytes per second 306.El 307.Pp 308The standard 309.Nm 310device display, with the 311.Fl I 312flag specified, shows the following statistics: 313.Pp 314.Bl -tag -width indent -compact 315.It KB/t 316kilobytes per transfer 317.It xfrs 318total number of transfers 319.It MB 320total number of megabytes transferred 321.El 322.Pp 323The extended 324.Nm 325device display, with the 326.Fl x 327flag specified, shows the following statistics: 328.Pp 329.Bl -tag -width indent -compact 330.It r/s 331read operations per second 332.It w/s 333write operations per second 334.It kr/s 335kilobytes read per second 336.It kw/s 337kilobytes write per second 338.It wait 339transactions queue length 340.It svc_t 341average duration of transactions, in milliseconds 342.It %b 343% of time the device had one or more outstanding transactions 344.El 345.Pp 346The old-style 347.Nm 348display (using 349.Fl o ) 350shows the following statistics: 351.Pp 352.Bl -tag -width indent -compact 353.It sps 354sectors transferred per second 355.It tps 356transfers per second 357.It msps 358average milliseconds per transaction 359.El 360.Pp 361The old-style 362.Nm 363display, with the 364.Fl I 365flag specified, shows the following statistics: 366.Pp 367.Bl -tag -width indent -compact 368.It blk 369total blocks/sectors transferred 370.It xfr 371total transfers 372.It msps 373average milliseconds per transaction 374.El 375.It cpu 376.Bl -tag -width indent -compact 377.It \&us 378% of cpu time in user mode 379.It \&ni 380% of cpu time in user mode running niced processes 381.It \&sy 382% of cpu time in system mode 383.It \&in 384% of cpu time in interrupt mode 385.It \&id 386% of cpu time in idle mode 387.El 388.El 389.Sh FILES 390.Bl -tag -width /boot/kernel/kernel -compact 391.It Pa /boot/kernel/kernel 392Default kernel namelist. 393.It Pa /dev/kmem 394Default memory file. 395.El 396.Sh EXAMPLES 397.Dl iostat -w 1 da0 da1 cd0 398.Pp 399Display statistics for the first two Direct Access devices and the first 400CDROM device every second ad infinitum. 401.Pp 402.Dl iostat -c 2 403.Pp 404Display the statistics for the first four devices in the system twice, with 405a one second display interval. 406.Pp 407.Dl iostat -t da -t cd -w 1 408.Pp 409Display statistics for all CDROM and Direct Access devices every second 410ad infinitum. 411.Pp 412.Dl iostat -t da,scsi,pass -t cd,scsi,pass 413.Pp 414Display statistics once for all SCSI passthrough devices that provide access 415to either Direct Access or CDROM devices. 416.Pp 417.Dl iostat -h -n 8 -w 1 418.Pp 419Display up to 8 devices with the most I/O every second ad infinitum. 420.Pp 421.Dl iostat -dh -t da -w 1 422.Pp 423Omit the TTY and CPU displays, show devices in order of performance and 424show only Direct Access devices every second ad infinitum. 425.Pp 426.Dl iostat -Iw 3 427.Pp 428Display total statistics every three seconds ad infinitum. 429.Pp 430.Dl iostat -odICTw 2 -c 9 431.Pp 432Display total statistics using the old-style output format 9 times, with 433a two second interval between each measurement/display. 434The 435.Fl d 436flag generally disables the TTY and CPU displays, but since the 437.Fl T 438and 439.Fl C 440flags are given, the TTY and CPU displays will be displayed. 441.Sh SEE ALSO 442.Xr fstat 1 , 443.Xr netstat 1 , 444.Xr nfsstat 1 , 445.Xr ps 1 , 446.Xr systat 1 , 447.Xr devstat 3 , 448.Xr gstat 8 , 449.Xr pstat 8 , 450.Xr vmstat 8 451.Pp 452The sections starting with ``Interpreting system activity'' in 453.%T "Installing and Operating 4.3BSD" . 454.Sh HISTORY 455This version of 456.Nm 457first appeared in 458.Fx 3.0 . 459.Sh AUTHORS 460.An Kenneth Merry Aq ken@FreeBSD.org 461.Sh BUGS 462The use of 463.Nm 464as a debugging tool for crash dumps is probably limited because there is 465currently no way to get statistics that only cover the time immediately before 466the crash. 467