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 iostat(1)							   iostat(1)




 NAME
      iostat - report I/O statistics

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

 DESCRIPTION
      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
      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 Release 11i: November 2000






 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
      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
      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
      iostat was developed by the University of California, Berkeley, and
      HP.

 FILES
      /usr/include/sys/param.h

 SEE ALSO
      vmstat(1).












 Hewlett-Packard Company	    - 2 -   HP-UX Release 11i: November 2000