xref: /dragonfly/usr.sbin/iostat/iostat.8 (revision c03f08f3) 
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2.\" Copyright (c) 1997 Kenneth D. Merry.
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28.\" $FreeBSD: src/usr.sbin/iostat/iostat.8,v 1.11.2.9 2002/12/29 16:35:41 schweikh Exp $
29.\" $DragonFly: src/usr.sbin/iostat/iostat.8,v 1.4 2005/09/01 19:08:38 swildner Exp $
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62.\"	@(#)iostat.8	8.1 (Berkeley) 6/6/93
63.\"
64.Dd December 22, 1997
65.Dt IOSTAT 8
66.Os
67.Sh NAME
68.Nm iostat
69.Nd report
70.Tn I/O
71statistics
72.Sh SYNOPSIS
73.Nm
74.Op Fl CdhKIoT
75.Op Fl c Ar count
76.Op Fl n Ar devs
77.Oo
78.Fl t
79.Sm off
80.Ar type , if , pass
81.Sm on
82.Oc
83.Op Fl w Ar wait
84.Op Ar drives
85.Sh DESCRIPTION
86.Nm Iostat
87displays kernel
88.Tn I/O
89statistics on terminal, device and cpu
90operations.
91.Pp
92The options are as follows:
93.Bl -tag -width flag
94.It Fl c
95Repeat the display
96.Ar count
97times.
98If no
99.Ar wait
100interval is specified, the default is 1 second.
101.It Fl C
102Display CPU statistics.
103This is on by default, unless
104.Fl d
105is specified.
106.It Fl d
107Display only device statistics.
108If this flag is turned on, only device statistics will be displayed, unless
109.Fl C
110or
111.Fl T
112is also specified to enable the display of CPU or TTY statistics.
113.It Fl h
114Put
115.Nm
116in
117.Sq top
118mode.
119In this mode,
120.Nm
121will show devices in order from highest to lowest bytes
122per measurement cycle.
123.It Fl I
124Display total statistics for a given time period, rather than average
125statistics for each second during that time period.
126.It Fl K
127In the blocks transferred display (-o), display block count in kilobytes rather
128then the device native block size.
129.It Fl n
130Display up to
131.Ar devs
132number of devices.
133.Nm
134will display fewer devices if there aren't
135.Ar devs
136devices present.
137.It Fl o
138Display old-style
139.Nm
140device statistics.
141Sectors per second, transfers per second, and milliseconds per seek are
142displayed.
143If
144.Fl I
145is specified, total blocks/sectors, total transfers, and
146milliseconds per seek are displayed.
147.It Fl t
148Specify which types of devices to display.
149There are three different categories of devices:
150.Pp
151.Bl -tag -width indent -compact
152.It device type:
153.Bl -tag -width 9n -compact
154.It da
155Direct Access devices
156.It sa
157Sequential Access devices
158.It printer
159Printers
160.It proc
161Processor devices
162.It worm
163Write Once Read Multiple devices
164.It cd
165CD devices
166.It scanner
167Scanner devices
168.It optical
169Optical Memory devices
170.It changer
171Medium Changer devices
172.It comm
173Communication devices
174.It array
175Storage Array devices
176.It enclosure
177Enclosure Services devices
178.It floppy
179Floppy devices
180.El
181.Pp
182.It interface:
183.Bl -tag -width 9n -compact
184.It IDE
185Integrated Drive Electronics devices
186.It SCSI
187Small Computer System Interface devices
188.It other
189Any other device interface
190.El
191.Pp
192.It passthrough:
193.Bl -tag -width 9n -compact
194.It pass
195Passthrough devices
196.El
197.El
198.Pp
199The user must specify at least one device type, and may specify at most
200one device type from each category.
201Multiple device types in a single device type statement must be separated by
202commas.
203.Pp
204Any number of
205.Fl t
206arguments may be specified on the command line.
207All
208.Fl t
209arguments are ORed together to form a matching expression against which
210all devices in the system are compared.
211Any device that fully matches any
212.Fl t
213argument will be included in the
214.Nm
215output, up to the number of devices that can be displayed in
21680 columns, or the maximum number of devices specified by the user.
217.It Fl T
218Display TTY statistics.
219This is on by default, unless
220.Fl d
221is specified.
222.It Fl w
223Pause
224.Ar wait
225seconds between each display.
226If no repeat
227.Ar count
228is specified, the default is infinity.
229.El
230.Pp
231.Nm Iostat
232displays its information in the following format:
233.Bl -tag -width flag
234.It tty
235.Bl -tag -width indent -compact
236.It tin
237characters read from terminals
238.It tout
239characters written to terminals
240.El
241.It devices
242Device operations.
243The header of the field is the device name and unit number.
244.Nm
245will display as many devices as will fit in a standard 80 column screen, or
246the maximum number of devices in the system, whichever is smaller.
247If
248.Fl n
249is specified on the command line,
250.Nm
251will display the smaller of the
252requested number of devices, and the maximum number of devices in the system.
253To force
254.Nm
255to display specific drives, their names may be supplied on the command
256line.
257.Nm
258will not display more devices than will fit in an 80 column screen, unless
259the
260.Fl n
261argument is given on the command line to specify a maximum number of
262devices to display.
263If fewer devices are specified on the command line than will fit in an 80
264column screen,
265.Nm
266will show only the specified devices.
267.Pp
268The standard
269.Nm
270device display shows the following statistics:
271.Pp
272.Bl -tag -width indent -compact
273.It KB/t
274kilobytes per transfer
275.It tps
276transfers per second
277.It MB/s
278megabytes per second
279.El
280.Pp
281The standard
282.Nm
283device display, with the
284.Fl I
285flag specified, shows the following statistics:
286.Pp
287.Bl -tag -width indent -compact
288.It KB/t
289kilobytes per transfer
290.It xfrs
291total number of transfers
292.It MB
293total number of megabytes transferred
294.El
295.Pp
296The old-style
297.Nm
298display (using
299.Fl o )
300shows the following statistics:
301.Pp
302.Bl -tag -width indent -compact
303.It sps
304sectors transferred per second
305.It tps
306transfers per second
307.It msps
308average milliseconds per transaction
309.El
310.Pp
311The old-style
312.Nm
313display, with the
314.Fl I
315flag specified, shows the following statistics:
316.Pp
317.Bl -tag -width indent -compact
318.It blk
319total blocks/sectors transferred
320.It xfr
321total transfers
322.It msps
323average milliseconds per transaction
324.El
325.It cpu
326.Bl -tag -width indent -compact
327.It \&us
328% of cpu time in user mode
329.It \&ni
330% of cpu time in user mode running niced processes
331.It \&sy
332% of cpu time in system mode
333.It \&in
334% of cpu time in interrupt mode
335.It \&id
336% of cpu time in idle mode
337.El
338.El
339.Sh EXAMPLES
340.Dl iostat -w 1 da0 da1 cd0
341.Pp
342Display statistics for the first two Direct Access devices and the first
343CDROM device every second ad infinitum.
344.Pp
345.Dl iostat -c 2
346.Pp
347Display the statistics for the first four devices in the system twice, with
348a one second display interval.
349.Pp
350.Dl iostat -t da -t cd -w 1
351.Pp
352Display statistics for all CDROM and Direct Access devices every second
353ad infinitum.
354.Pp
355.Dl iostat -t da,scsi,pass -t cd,scsi,pass
356.Pp
357Display statistics once for all SCSI passthrough devices that provide access
358to either Direct Access or CDROM devices.
359.Pp
360.Dl iostat -h -n 8 -w 1
361.Pp
362Display up to 8 devices with the most I/O every second ad infinitum.
363.Pp
364.Dl iostat -dh -t da -w 1
365.Pp
366Omit the TTY and CPU displays, show devices in order of performance and
367show only Direct Access devices every second ad infinitum.
368.Pp
369.Dl iostat -Iw 3
370.Pp
371Display total statistics every three seconds ad infinitum.
372.Pp
373.Dl iostat -odICTw 2 -c 9
374.Pp
375Display total statistics using the old-style output format 9 times, with
376a two second interval between each measurement/display.
377The
378.Fl d
379flag generally disables the TTY and CPU displays, but since the
380.Fl T
381and
382.Fl C
383flags are given, the TTY and CPU displays will be displayed.
384.Sh SEE ALSO
385.Xr fstat 1 ,
386.Xr netstat 1 ,
387.Xr nfsstat 1 ,
388.Xr ps 1 ,
389.Xr systat 1 ,
390.Xr pstat 8 ,
391.Xr vmstat 8
392.Pp
393The sections starting with ``Interpreting system activity'' in
394.%T "Installing and Operating 4.3BSD" .
395.Sh HISTORY
396This version of
397.Nm
398first appeared in
399.Fx 3.0 .
400.Sh AUTHORS
401.An Kenneth Merry Aq ken@FreeBSD.org
402