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

NAME
     iostat -- report I/O statistics

SYNOPSIS
     iostat [-CdDITx] [-c count] [-M core] [-N system] [-w wait] [drives]

DESCRIPTION
     iostat displays kernel I/O statistics on terminal, disk and CPU opera-
     tions.  By default, iostat displays one line of statistics averaged over
     the machine's run time.  The use of -c presents successive lines averaged
     over the wait period.  The -I option causes iostat to print raw, unaver-
     aged values.

     Only the last disk option specified (-d, -D, or -x) is used.

     The options are as follows:

     -c count    Repeat the display count times.  Unless the -I flag is in
                 effect, 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 wait interval is specified, the default is 1
                 second.

     -C          Show CPU statistics.  This is enabled by default unless the
                 -d, -D, -T, or -x flags are used.

     -d          Show disk statistics.  This is the default.  Displays kilo-
                 bytes per transfer, number of transfers, and megabytes trans-
                 ferred.  Use of this flag disables display of CPU and tty
                 statistics.

     -D          Show alternative disk statistics.  Displays kilobytes trans-
                 ferred, number of transfers, and time spent in transfers.
                 Use of this flag disables the default display.

     -I          Show the running total values, rather than an average.

     -M core     Extract values associated with the name list from the speci-
                 fied core instead of the default ``/dev/mem''.

     -N system   Extract the name list from the specified system instead of
                 the default ``/netbsd''.

     -T          Show tty statistics.  This is enabled by default unless the
                 -C, -d, or -D flags are used.

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

     -x          Show extended disk statistics.  Each disk is displayed on a
                 line of its own with all available statistics.  This option
                 overrides all other display options, and all disks are dis-
                 played unless specific disks are provided as arguments.
                 Additionally, separate read and write statistics are dis-
                 played.

     iostat displays its information in the following format:

     tty
           tin     characters read from terminals
           tout    characters written to terminals

     disks
           Disk operations.  The header of the field is the disk name and unit
           number.  If more than four disk drives are configured in the sys-
           tem, iostat displays only the first four drives.  To force iostat
           to display specific drives, their names may be supplied on the com-
           mand line.

           KB/t    Kilobytes transferred per disk transfer
           t/s     transfers per second
           MB/s    Megabytes transferred per second

           The alternative display format, (selected with -D), presents the
           following values.
           KB      Kilobytes transferred
           xfr     Disk transfers
           time    Seconds spent in disk activity

     cpu
           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

FILES
     /netbsd   Default kernel namelist.
     /dev/mem  Default memory file.

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

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

HISTORY
     iostat appeared in Version 6 AT&T UNIX.  The -x option was added in
     NetBSD 1.4.

NetBSD 5.0_STABLE                March 1, 2003               NetBSD 5.0_STABLE
