2 .\" Copyright (c) 1997 Kenneth D. Merry.
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61 .\" @(#)iostat.8 8.1 (Berkeley) 6/6/93
89 utility displays kernel
91 statistics on terminal, device and cpu operations.
92 The first statistics that are printed are averaged over the system uptime.
93 To get information about the current activity, a suitable wait time should
94 be specified, so that the subsequent sets of printed statistics will be
95 averaged over that time.
97 The options are as follows:
105 interval is specified, the default is 1 second.
107 Display CPU statistics.
108 This is on by default, unless
112 Display only device statistics.
113 If this flag is turned on, only device statistics will be displayed, unless
117 is also specfied to enable the display of CPU or TTY statistics.
126 will show devices in order from highest to lowest bytes
127 per measurement cycle.
129 Display total statstics for a given time period, rather than average
130 statistics for each second during that time period.
132 In the blocks transfered display (-o), display block count in kilobytes rather
133 then the device native block size.
135 Extract values associated with the name list from the specified core
136 instead of the default
144 utility will display fewer devices if there aren't
148 Extract the name list from the specified system instead of the default
149 .Dq Pa /boot/kernel/kernel .
154 Sectors per second, transfers per second, and miliseconds per seek are
158 is specified, total blocks/sectors, total transfers, and
159 miliseconds per seek are displayed.
161 Specify which types of devices to display.
162 There are three different categories of devices:
164 .Bl -tag -width indent -compact
166 .Bl -tag -width 9n -compact
168 Direct Access devices
170 Sequential Access devices
176 Write Once Read Multiple devices
182 Optical Memory devices
184 Medium Changer devices
186 Communication devices
188 Storage Array devices
190 Enclosure Services devices
196 .Bl -tag -width 9n -compact
198 Integrated Drive Electronics devices
200 Small Computer System Interface devices
202 Any other device interface
206 .Bl -tag -width 9n -compact
212 The user must specify at least one device type, and may specify at most
213 one device type from each category.
214 Multiple device types in a single device type statement must be separated by
219 arguments may be specified on the command line.
222 arguments are ORed together to form a matching expression against which
223 all devices in the system are compared.
224 Any device that fully matches any
226 argument will be included in the
228 output, up to the number of devices that can be displayed in
229 80 columns, or the maximum number of devices specified by the user.
231 Display TTY statistics.
232 This is on by default, unless
238 seconds between each display.
241 is specified, the default is infinity.
243 Display a usage statement and exit.
248 utility displays its information in the following format:
251 .Bl -tag -width indent -compact
253 characters read from terminals
255 characters written to terminals
259 The header of the field is the device name and unit number.
263 will display as many devices as will fit in a standard 80 column screen, or
264 the maximum number of devices in the system, whichever is smaller.
267 is specified on the command line,
269 will display the smaller of the
270 requested number of devices, and the maximum number of devices in the system.
273 to display specific drives, their names may be supplied on the command
278 will not display more devices than will fit in an 80 column screen, unless
281 argument is given on the command line to specify a maximum number of
283 If fewer devices are specified on the command line than will fit in an 80
286 will show only the specified devices.
290 device display shows the following statistics:
292 .Bl -tag -width indent -compact
294 kilobytes per transfer
303 device display, with the
305 flag specified, shows the following statistics:
307 .Bl -tag -width indent -compact
309 kilobytes per transfer
311 total number of transfers
313 total number of megabytes transferred
320 shows the following statistics:
322 .Bl -tag -width indent -compact
324 sectors transferred per second
328 average milliseconds per transaction
335 flag specified, shows the following statistics:
337 .Bl -tag -width indent -compact
339 total blocks/sectors transferred
343 average milliseconds per transaction
346 .Bl -tag -width indent -compact
348 % of cpu time in user mode
350 % of cpu time in user mode running niced processes
352 % of cpu time in system mode
354 % of cpu time in interrupt mode
356 % of cpu time in idle mode
360 .Bl -tag -width /boot/kernel/kernel -compact
361 .It Pa /boot/kernel/kernel
362 Default kernel namelist.
367 .Dl iostat -w 1 da0 da1 cd0
369 Display statistics for the first two Direct Access devices and the first
370 CDROM device every second ad infinitum.
374 Display the statistics for the first four devices in the system twice, with
375 a one second display interval.
377 .Dl iostat -t da -t cd -w 1
379 Display statistics for all CDROM and Direct Access devices every second
382 .Dl iostat -t da,scsi,pass -t cd,scsi,pass
384 Display statistics once for all SCSI passthrough devices that provide access
385 to either Direct Access or CDROM devices.
387 .Dl iostat -h -n 8 -w 1
389 Display up to 8 devices with the most I/O every second ad infinitum.
391 .Dl iostat -dh -t da -w 1
393 Omit the TTY and CPU displays, show devices in order of performance and
394 show only Direct Access devices every second ad infinitum.
398 Display total statistics every three seconds ad infinitum.
400 .Dl iostat -odICTw 2 -c 9
402 Display total statistics using the old-style output format 9 times, with
403 a two second interval between each measurement/display.
406 flag generally disables the TTY and CPU displays, but since the
410 flags are given, the TTY and CPU displays will be displayed.
420 The sections starting with ``Interpreting system activity'' in
421 .%T "Installing and Operating 4.3BSD" .
430 as a debugging tool for crash dumps is probably limited because there is
431 currently no way to get statistics that only cover the time immediately before
434 .An Kenneth Merry Aq ken@FreeBSD.org