2 .\" Copyright (c) 1997 Kenneth D. Merry.
3 .\" All rights reserved.
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61 .\" @(#)iostat.8 8.1 (Berkeley) 6/6/93
90 statistics on terminal, device and cpu operations.
91 The first statistics that are printed are averaged over the system uptime.
92 To get information about the current activity, a suitable wait time should
93 be specified, so that the subsequent sets of printed statistics will be
94 averaged over that time.
96 The options are as follows:
104 interval is specified, the default is 1 second.
106 Display CPU statistics.
107 This is on by default, unless
111 Display only device statistics.
112 If this flag is turned on, only device statistics will be displayed, unless
116 is also specfied to enable the display of CPU or TTY statistics.
125 will show devices in order from highest to lowest bytes
126 per measurement cycle.
128 Display total statstics for a given time period, rather than average
129 statistics for each second during that time period.
131 In the blocks transfered display (-o), display block count in kilobytes rather
132 then the device native block size.
134 Extract values associated with the name list from the specified core
135 instead of the default
142 will display fewer devices if there aren't
146 Extract the name list from the specified system instead of the default
147 .Dq Pa /boot/kernel/kernel .
152 Sectors per second, transfers per second, and miliseconds per seek are
156 is specified, total blocks/sectors, total transfers, and
157 miliseconds per seek are displayed.
159 Specify which types of devices to display.
160 There are three different categories of devices:
162 .Bl -tag -width indent -compact
164 .Bl -tag -width 9n -compact
166 Direct Access devices
168 Sequential Access devices
174 Write Once Read Multiple devices
180 Optical Memory devices
182 Medium Changer devices
184 Communication devices
186 Storage Array devices
188 Enclosure Services devices
194 .Bl -tag -width 9n -compact
196 Integrated Drive Electronics devices
198 Small Computer System Interface devices
200 Any other device interface
204 .Bl -tag -width 9n -compact
210 The user must specify at least one device type, and may specify at most
211 one device type from each category.
212 Multiple device types in a single device type statement must be separated by
217 arguments may be specified on the command line.
220 arguments are ORed together to form a matching expression against which
221 all devices in the system are compared.
222 Any device that fully matches any
224 argument will be included in the
226 output, up to the number of devices that can be displayed in
227 80 columns, or the maximum number of devices specified by the user.
229 Display TTY statistics.
230 This is on by default, unless
236 seconds between each display.
239 is specified, the default is infinity.
241 Display a usage statement and exit.
245 displays its information in the following format:
248 .Bl -tag -width indent -compact
250 characters read from terminals
252 characters written to terminals
256 The header of the field is the device name and unit number.
258 will display as many devices as will fit in a standard 80 column screen, or
259 the maximum number of devices in the system, whichever is smaller.
262 is specified on the command line,
264 will display the smaller of the
265 requested number of devices, and the maximum number of devices in the system.
268 to display specific drives, their names may be supplied on the command
271 will not display more devices than will fit in an 80 column screen, unless
274 argument is given on the command line to specify a maximum number of
276 If fewer devices are specified on the command line than will fit in an 80
279 will show only the specified devices.
283 device display shows the following statistics:
285 .Bl -tag -width indent -compact
287 kilobytes per transfer
296 device display, with the
298 flag specified, shows the following statistics:
300 .Bl -tag -width indent -compact
302 kilobytes per transfer
304 total number of transfers
306 total number of megabytes transferred
313 shows the following statistics:
315 .Bl -tag -width indent -compact
317 sectors transferred per second
321 average milliseconds per transaction
328 flag specified, shows the following statistics:
330 .Bl -tag -width indent -compact
332 total blocks/sectors transferred
336 average milliseconds per transaction
339 .Bl -tag -width indent -compact
341 % of cpu time in user mode
343 % of cpu time in user mode running niced processes
345 % of cpu time in system mode
347 % of cpu time in interrupt mode
349 % of cpu time in idle mode
353 .Bl -tag -width /boot/kernel/kernel -compact
354 .It Pa /boot/kernel/kernel
355 Default kernel namelist.
360 .Dl iostat -w 1 da0 da1 cd0
362 Display statistics for the first two Direct Access devices and the first
363 CDROM device every second ad infinitum.
367 Display the statistics for the first four devices in the system twice, with
368 a one second display interval.
370 .Dl iostat -t da -t cd -w 1
372 Display statistics for all CDROM and Direct Access devices every second
375 .Dl iostat -t da,scsi,pass -t cd,scsi,pass
377 Display statistics once for all SCSI passthrough devices that provide access
378 to either Direct Access or CDROM devices.
380 .Dl iostat -h -n 8 -w 1
382 Display up to 8 devices with the most I/O every second ad infinitum.
384 .Dl iostat -dh -t da -w 1
386 Omit the TTY and CPU displays, show devices in order of performance and
387 show only Direct Access devices every second ad infinitum.
391 Display total statistics every three seconds ad infinitum.
393 .Dl iostat -odICTw 2 -c 9
395 Display total statistics using the old-style output format 9 times, with
396 a two second interval between each measurement/display.
399 flag generally disables the TTY and CPU displays, but since the
403 flags are given, the TTY and CPU displays will be displayed.
413 The sections starting with ``Interpreting system activity'' in
414 .%T "Installing and Operating 4.3BSD" .
423 as a debugging tool for crash dumps is probably limited because there is
424 currently no way to get statistics that only cover the time immediately before
427 .An Kenneth Merry Aq ken@FreeBSD.org