usr/src/usr.sbin/iostat/iostat.8

.\" Copyright (c) 1985, 1991 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" %sccs.include.redist.roff%
.\"
.\"     @(#)iostat.8    6.8 (Berkeley) %G%
.\"
.TH IOSTAT 8 ""
.UC 4
.SH NAME
iostat \- report I/O statistics
.SH SYNOPSIS
.nf
.ft B
iostat [ \-c count ] [ \-M core ] [ \-N system ]
.ti +5
[ \-w wait ] [ drives ]
.ft R
.fi
.SH DESCRIPTION
.I Iostat
reports certain kernel statistics kept about terminal, disk and cpu
activity.
.PP
The options are as follows:
.TP
\-c
Repeat the display
.I count
times.
The first display is for the time since a reboot and each subsequent
report is for the time period since the last display.
If no
.I wait
interval is specified, the default is 1 second.
.TP
\-M
Extract values associated with the name list from the specified core
instead of the default ``/dev/kmem''.
.TP
\-N
Extract the name list from the specified system instead of the default
``/vmunix''.
.TP
\-w
Pause
.I wait
seconds between each display.
If no repeat
.I count
is specified, the default is infinity.
.PP
.I Iostat
displays its information in the following format:
.TP
tty
.nf
.RS
tin     characters read from terminals
tout    characters written to terminals
.RE
.fi
.TP
disks
Disk operations (this field is system dependent).
The header of the field is the disk name and unit number.
If more than four disk drives are configured in the system,
.I iostat
displays only the first four drives.
To force
.I iostat
to display specific drives, their names may be supplied on the command
line.
.sp
.nf
.RS
sps     sectors transferred per second
tps     transfers per second
msps    milliseconds per average seek (including implied
        seeks and rotational latency)
.RE
.fi
.TP
cpu
.nf
.RS
us      % of cpu time in user mode
ni      % of cpu time in user mode running niced processes
sy      % of cpu time in system mode
id      % of cpu time in idle mode
.RE
.fi
.SH FILES
.ta \w'/dev/kmem  'u
/vmunix default kernel namelist
.br
/dev/kmem       default memory file
.SH SEE ALSO
.IR fstat (1),
.IR netstat (1),
.IR nfsstat (1),
.IR ps (1),
.IR systat (1),
.IR vmstat (1),
.IR pstat (8)
.sp
The sections starting with ``Interpreting system activity'' in
.IR "Installing and Operating 4.3BSD" .