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Annotation of 43BSDReno/usr.sbin/iostat/iostat.8, revision 1.1.1.1

1.1       root        1: .\" Copyright (c) 1980 Regents of the University of California.
                      2: .\" All rights reserved.  The Berkeley software License Agreement
                      3: .\" specifies the terms and conditions for redistribution.
                      4: .\"
                      5: .\"    @(#)iostat.8    6.2 (Berkeley) 6/22/90
                      6: .\"
                      7: .TH IOSTAT 8 "June 22, 1990"
                      8: .UC 4
                      9: .SH NAME
                     10: iostat \- report I/O statistics
                     11: .SH SYNOPSIS
                     12: .B iostat
                     13: [ drives ]
                     14: [ interval [ count ] ]
                     15: .SH DESCRIPTION
                     16: .I Iostat
                     17: iteratively reports the number of characters read and written to terminals
                     18: per second,
                     19: and, for each disk, the number of transfers per second, kilobytes
                     20: transferred per second,
                     21: and the milliseconds per average seek.
                     22: It also gives the percentage of time the system has
                     23: spent in user mode, in user mode running low priority (niced) processes,
                     24: in system mode, and idling.
                     25: .PP
                     26: To compute this information, for each disk, seeks and data transfer completions
                     27: and number of words transferred are counted;
                     28: for terminals collectively, the number
                     29: of input and output characters are counted.
                     30: Also, each sixtieth of a second,
                     31: the state of each disk is examined
                     32: and a tally is made if the disk is active.
                     33: From these numbers and given the transfer rates
                     34: of the devices it is possible to determine
                     35: average seek times for each device.
                     36: .PP
                     37: The optional
                     38: .I interval
                     39: argument causes
                     40: .I iostat
                     41: to report once each
                     42: .I interval
                     43: seconds.
                     44: The first report is for  all time since a reboot and each
                     45: subsequent report is for the last interval only.
                     46: .PP
                     47: The optional
                     48: .I count
                     49: argument restricts the number of reports.
                     50: .PP
                     51: If more than 4 disk drives are configured in the system,
                     52: .I iostat
                     53: displays only the first 4 drives, with priority given
                     54: to Massbus disk drives (i.e. if both Unibus and Massbus
                     55: drives are present and the total number of drives exceeds
                     56: 4, then some number of Unibus drives will not be displayed
                     57: in favor of the Massbus drives).  To force
                     58: .I iostat
                     59: to display specific drives, their names may be supplied on
                     60: the command line.
                     61: .SH FILES
                     62: /dev/kmem
                     63: .br
                     64: /vmunix
                     65: .SH SEE ALSO
                     66: vmstat(1)

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