iostat(1)                                                         iostat(1)




 NAME    [Toc]    [Back]
      iostat - report I/O statistics

 SYNOPSIS    [Toc]    [Back]
      iostat [-t] [interval [count]]

 DESCRIPTION    [Toc]    [Back]
      iostat iteratively reports I/O statistics for each active disk on the
      system.  Disk data is arranged in a four-column format:
                Column Heading   Interpretation
                    device       Device name
                    bps          Kilobytes transferred per second
                    sps          Number of seeks per second
                    msps         Milliseconds per average seek

      If two or more disks are present, data is presented on successive
      lines for each disk.

      To compute this information, seeks, data transfer completions, and the
      number of words transferred are counted for each disk.  Also, the
      state of each disk is examined HZ times per second (as defined in
      <sys/param.h>) and a tally is made if the disk is active.  These
      numbers can be combined with the transfer rates of each device to
      determine average seek times for each device.

      With the advent of new disk technologies, such as data striping, where
      a single data transfer is spread across several disks, the number of
      milliseconds per average seek becomes impossible to compute
      accurately.  At best it is only an approximation, varying greatly,
      based on several dynamic system conditions.  For this reason and to
      maintain backward compatibility, the milliseconds per average seek (
      msps ) field is set to the value 1.0.

    Options    [Toc]    [Back]
      iostat recognizes the following options and command-line arguments:

           -t          Report terminal statistics as well as disk
                       statistics.  Terminal statistics include:

                            tin    Number of characters read from terminals.
                            tout   Number of characters written to
                                   terminals.
                            us     Percentage of time system (active
                                   processors) has spent in user mode.
                            ni     Percentage of time system (active
                                   processors) has spent in user mode
                                   running low-priority (nice) processes.
                            sy     Percentage of time system (active
                                   processors) has spent in system mode.
                            id     Percentage of time system (active
                                   processors) has spent idling.



 Hewlett-Packard Company            - 1 -   HP-UX 11i Version 2: August 2003






 iostat(1)                                                         iostat(1)




           interval    Display successive lines which are summaries of the
                       last interval seconds.  The first line reported is
                       for the time since a reboot and each subsequent line
                       is for the last interval only.

           count       Repeat the statistics count times.

 EXAMPLES    [Toc]    [Back]
      Show current I/O statistics for all disks:

           iostat

      Display I/O statistics for all disks every 10 seconds until INTERRUPT
      or QUIT is pressed:

           iostat 10

      Display I/O statistics for all disks every 10 seconds and terminate
      after 5 successive readings:

           iostat 10 5

      Display I/O statistics for all disks every 10 seconds, also show
      terminal and processor statistics, and terminate after 5 successive
      readings:

           iostat -t 10 5

 WARNINGS    [Toc]    [Back]
      Users of iostat must not rely on the exact field widths and spacing of
      its output, as these will vary depending on the system, the release of
      HP-UX, and the data to be displayed.

 AUTHOR    [Toc]    [Back]
      iostat was developed by the University of California, Berkeley, and
      HP.

 FILES    [Toc]    [Back]
      /usr/include/sys/param.h

 SEE ALSO    [Toc]    [Back]
      vmstat(1).


 Hewlett-Packard Company            - 2 -   HP-UX 11i Version 2: August 2003