366 lines
8.9 KiB
Groff
366 lines
8.9 KiB
Groff
.\" $NetBSD: iostat.8,v 1.30 2023/07/28 12:03:33 wiz Exp $
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.\"
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.\" Copyright (c) 1985, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" from: @(#)iostat.8 8.1 (Berkeley) 6/6/93
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.\"
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.Dd July 28, 2023
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.Dt IOSTAT 8
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.Os
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.Sh NAME
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.Nm iostat
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.Nd report I/O statistics
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.Sh SYNOPSIS
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.Nm
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.Op Fl CDdITXxyz
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.Op Fl c Ar count
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.Op Fl H Ar height
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.Op Fl W Ar width
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.Op Fl w Ar wait
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.Op Ar drives
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.Sh DESCRIPTION
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.Nm
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displays kernel I/O statistics on terminal, disk and CPU operations.
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By default,
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.Nm
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displays one line of statistics averaged over the machine's run time.
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The use of
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.Fl c
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or
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.Fl w
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presents successive lines averaged over the
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.Ar wait
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period.
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The
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.Fl I
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option causes
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.Nm
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to print raw, unaveraged values (totals).
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.Pp
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Only the last disk option specified
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.Fl ( d ,
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.Fl D ,
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.Fl X ,
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.Fl x ,
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or
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.Fl y )
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is used.
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.Pp
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The options are as follows:
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.Bl -tag -width XNXsystemX
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.It Fl C
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Show CPU statistics.
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This is enabled by default unless any of the
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.Fl D ,
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.Fl d ,
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.Fl T ,
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.Fl X ,
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.Fl x ,
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or
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.Fl y
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flags are used.
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.It Fl c Ar count
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Repeat the display
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.Ar count
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times.
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Unless the
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.Fl I
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flag is in effect, the first display is for the time since a reboot and
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each subsequent report is for the time period since the last display.
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If no
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.Ar wait
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interval is specified, the default is 1 second.
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.It Fl D
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Show alternative disk statistics.
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Displays
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number of transfers,
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kilobytes transferred,
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and
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time spent in transfers,
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during the
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.Ar wait
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period (or since boot with
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.Fl I ) .
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Use of this flag disables the default display.
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.It Fl d
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Show disk statistics.
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This is the default.
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Displays
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number of transfers per second,
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kilobytes per transfer,
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and
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megabytes transferred per second.
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Use of this flag disables the default display of CPU and tty statistics.
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.It Fl H Ar height
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Set the page size (length, or height) explicitly, as the number of lines,
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.Ar height .
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If not set, the page length is taken from the environment variable
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.Ev LINES
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if set, or from the terminal (window) size, if output is to a terminal
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and its size is set,
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and otherwise defaults to 20.
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If explicitly set to zero, pages are considered to be infinitely long.
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This parameter determines the frequency at which repeated headers are output.
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If the value is greater than zero, but too small for the header, along with
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one output set, then a new header will be produced for each set of output.
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.It Fl I
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Show the running total values, rather than an average.
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.ig ii
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.It Fl i
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Like
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.Fl I
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except the totals shown are those since
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.Nm
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started running, rather than since the system booted.
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In this case the first output would necessarily be zero,
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so is suppressed.
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Consequently this option produces no output if neither
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.Fl c
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nor
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.Fl w
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is given.
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.ii
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.It Fl T
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Show tty statistics.
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This is enabled by default unless one, or more, of the
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.Fl C ,
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.Fl D ,
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.Fl d ,
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.Fl X ,
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.Fl x ,
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or
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.Fl y
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flags are used.
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.ig uu
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.It Fl u
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When totals are being shown
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.Pq Fl I
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.ig ii
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.Po or
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.Fl i Pc
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.ii
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include a column after each relevant output column
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showing the difference between this output and the previous.
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These added columns will be blank in the first displayed output.
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.uu
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.It Fl W Ar width
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Set the page width explicitly, as the number of columns of characters,
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.Ar width .
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If not set, the page width is taken from the environment variable
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.Ev COLUMNS
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if set, or from the terminal (window) size, if output is to a terminal
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and its size is set,
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and otherwise defaults to 80.
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If explicitly set to 0, lines are considered infinitely long.
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This width is used only to determine the number of drives to display
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by default when no drive list is given.
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In other cases output will be as wide as needed to display the
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data requested.
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.It Fl w Ar wait
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Pause
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.Ar wait
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seconds between each display.
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If no repeat
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.Ar count
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is specified, the default is infinity.
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.It Fl X
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Show limited alternative disk statistics.
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Displays megabytes transferred, and time spent in transfers, during the
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.Ar wait
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period (or since boot with
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.Fl I ) .
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Use of this flag disables the default display.
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.It Fl x
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Show extended disk statistics.
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Each disk is displayed on a line of its own with all available
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statistics.
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This option overrides all other display options, and all
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disks are displayed unless specific disk names
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are provided as arguments.
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Additionally, separate read and write statistics are displayed.
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The
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.Fl C
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and
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.Fl T
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options are ignored with this output format.
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.It Fl y
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Shows the extended statistics (as with
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.Fl x )
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and additional queuing statistics.
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Output does not fit in an 80 column window.
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The
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.Fl C
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and
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.Fl T
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options are ignored with this output format.
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.It Fl z
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Replaces drive and CPU statistic outputs that are exactly zero with spaces.
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Note that zero values can still appear \(en this indicates a
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value that was not zero, but was rounded down so appears as zero.
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Drive output is replaced by spaces only when the drive did no
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input or output at all in the interval,
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or with
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.Fl I ,
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has never done any I/O.
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.El
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.Pp
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.Nm
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displays its information in the following format:
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.Bl -tag -width flag
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.It tty
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.Bl -tag -width indent -compact
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.It tin
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characters read from terminals
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.It tout
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characters written to terminals
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.El
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.It disks
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Disk operations.
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The header of the field is the disk name and unit number.
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If more drives are configured in the system that fit across the
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current display,
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.Nm
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displays only those drives that fit on the display.
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To force
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.Nm
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to display specific drives, they may be supplied on the command
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line, either as names or
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.Fn fnmatch
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patterns.
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.Pp
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.Bl -tag -width indent -compact
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.It t/s
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transfers per second
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.It KB/t
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Kilobytes transferred per disk transfer
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.It MB/s
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Megabytes transferred per second
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.El
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.Pp
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The alternative display format, (selected with
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.Fl D ) ,
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presents the following values:
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.Pp
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.Bl -tag -width indent -compact
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.It xfr
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Disk transfers
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.It KB
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Kilobytes transferred
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.It time
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Seconds spent in disk activity
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.El
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.Pp
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With the
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.Fl y
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flag, the following queuing measurements are added:
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.Pp
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.Bl -tag -width indent -compact
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.It wait
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Number of I/O requests queued up
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.It actv
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Number of currently active I/O requests
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.It wsvc_t
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Average waiting time of an I/O request in milliseconds
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.It asvc_t
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Average duration of an I/O request in milliseconds
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.It wtime
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Seconds spent in the waiting queue.
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Queuing data might not be available from all drivers
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and is then shown as zeros.
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.El
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.Pp
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With the
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.Fl X
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flag, the following queuing measurements are added:
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.Pp
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.Bl -tag -width indent -compact
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.It MB/s
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Megabytes transferred per second
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.It time
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Seconds spent in disk activity
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.El
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.It cpu
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.Bl -tag -width indent -compact
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.It \&us
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% of CPU time in user mode
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.It \&ni
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% of CPU time in user mode running niced processes
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.It \&sy
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% of CPU time in system mode
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.It \&in
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% of CPU time in interrupt mode
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.It \&id
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% of CPU time in idle mode
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.El
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.Pp
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Note that because of rounding, these percentages may
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appear to total more or less than 100.
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.El
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.Sh SEE ALSO
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.Xr fstat 1 ,
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.Xr netstat 1 ,
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.Xr nfsstat 1 ,
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.Xr ps 1 ,
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.Xr systat 1 ,
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.Xr vmstat 1 ,
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.Xr fnmatch 3 ,
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.Xr pstat 8
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.Pp
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The sections starting with ``Interpreting system activity'' in
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.%T "Installing and Operating 4.3BSD" .
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.Sh HISTORY
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.Nm
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appeared in
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.At v6 .
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The
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.Fl x
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option was added in
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.Nx 1.4 .
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Collection of queuing values and the
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.Fl y
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option were added in
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.Nx 8.0 .
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The
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.Fl X
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option was added in
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.Nx 11.0 .
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The archaic option format:
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.br
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.ti +3n
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.Nm
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.Op Ar drives ...
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.Oo Ar wait Oo Ar count Oc Oc
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.br
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remains supported (the first
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.Ar drive
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whose name starts with a digit is taken to be the
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.Ar wait
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period) but is deprecated,
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and may be removed in a future version,
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so should not be used.
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