IOSTAT(8) BSD System Manager's Manual IOSTAT(8)

NAME
     iioossttaatt - report I/O statistics

SYNOPSIS
     iioossttaatt [-CCddKKIIooTT??] [-cc count] [-nn devs] [-ww wait] [drives]

DESCRIPTION
     IIoossttaatt displays kernel I/O statistics on terminal, device and cpu opera-
     tions.  The first statistics that are printed are averaged over the sys-
     tem uptime.  To get information about the current activity, a suitable
     wait time should be specified, so that the subsequent sets of printed
     statistics will be averaged over that time.

     The options are as follows:

     -cc    Repeat the display count times.  If no wait interval is specified,
           the default is 1 second.

     -CC    Display CPU statistics.  This is on by default, unless -dd is speci-
           fied.

     -dd    Display only device statistics.  If this flag is turned on, only
           device statistics will be displayed, unless -CC or -TT is also spec-
           fied to enable the display of CPU or TTY statistics.

     -II    Display total statstics for a given time period, rather than aver-
           age statistics for each second during that time period.

     -KK    In the blocks transferred display (-o), display block count in
           kilobytes rather then the device native block size.

     -nn    Display up to devs number of devices.  iioossttaatt will display fewer
           devices if there aren't devs devices present.

     -oo    Display old-style iioossttaatt device statistics.  Sectors per second,
           transfers per second, and miliseconds per seek are displayed.  If
           -II is specified, total blocks/sectors, total transfers, and
           miliseconds per seek are displayed.

     -TT    Display TTY statistics.  This is on by default, unless -dd is speci-
           fied.

     -ww    Pause wait seconds between each display.  If no repeat count is
           specified, the default is infinity.

     -??    Display a usage statement and exit.

     IIoossttaatt displays its information in the following format:

     tty
           tin     characters read from terminals
           tout    characters written to terminals

     devices
           Device operations.  The header of the field is the device name and
           unit number.  iioossttaatt will display as many devices as will fit in a
           standard 80 column screen, or the maximum number of devices in the
           system, whichever is smaller.  If -nn is specified on the command
           line, iioossttaatt will display the smaller of the requested number of
           devices, and the maximum number of devices in the system.  To force
           iioossttaatt to display specific drives, their names may be supplied on
           the command line.  iioossttaatt will not display more devices than will
           fit in an 80 column screen, unless the -nn argument is given on the
           command line to specify a maximum number of devices to display, or
           the list of specified devices exceeds 80 columns.  If fewer devices
           are specified on the command line than will fit in an 80 column
           screen, iioossttaatt will show only the specified devices.

           The standard iioossttaatt device display shows the following statistics:

           KB/t    kilobytes per transfer
           tps     transfers per second
           MB/s    megabytes per second

           The standard iioossttaatt device display, with the -II flag specified,
           shows the following statistics:

           KB/t    kilobytes per transfer
           xfrs    total number of transfers
           MB      total number of megabytes transferred

           The old-style iioossttaatt display (using -oo) shows the following statis-
           tics:

           sps     sectors transferred per second
           tps     transfers per second
           msps    average milliseconds per transaction

           The old-style iioossttaatt display, with the -II flag specified, shows the
           following statistics:

           blk     total blocks/sectors transferred
           xfr     total transfers
           msps    average milliseconds per transaction

     cpu
           us      % of cpu time in user mode
           sy      % of cpu time in system mode
           id      % of cpu time in idle mode

EEXXAAMMPPLLEESS
           iostat -w 1 disk0 disk2

     Display statistics for the first and third disk devices device every sec-
     ond ad infinitum.

           iostat -c 2

     Display the statistics for the first four devices in the system twice,
     with a one second display interval.

           iostat -Iw 3

     Display total statistics every three seconds ad infinitum.

           iostat -odICTw 2 -c 9

     Display total statistics using the old-style output format 9 times, with
     a two second interval between each measurement/display.  The -dd flag gen-
     erally disables the TTY and CPU displays, but since the -TT and -CC flags
     are given, the TTY and CPU displays will be displayed.

SEE ALSO
     fstat(1), netstat(1), nfsstat(1), ps(1), pstat(8),

     The sections starting with ``Interpreting system activity'' in Installing
     and Operating 4.3BSD.

HISTORY     This version of iioossttaatt first appeared in FFrreeeeBBSSDD 33..00.

BSD                           September 27, 2001                           BSD