iostat(1)						      General Commands Manual							 iostat(1)

NAME

       iostat - report I/O statistics

SYNOPSIS

       [interval [count]]

DESCRIPTION

       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 times per second (as defined in 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 field is set
       to the value 1.0.

   Options
       recognizes the following options and command-line arguments:

	      Report terminal statistics as well as disk (or lunpath) statistics.
			  When used with the option, lunpath and terminal statistics are displayed.  Terminal statistics include:

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

	      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.

	      Report active lunpath statistics.  When used with the
			  option,  lunpath  and  terminal  statistics are reported.  The lunpaths are not displayed in any specific order, and the
			  current order may change in future releases.	Lunpath data is arranged in a four-column format:

			  symbolic name of the lunpath of the form:
				      diskm_lunpathn, where m is the instance number of LUN and n is the instance number of lunpath.  For example,
				      in  disk47_lunpath7,  m  is 47 and n is 7.  These instance numbers are displayed by using the option for the
				      LUN and lunpath entries.	For more information on LUN and lunpath hardware path, refer to intro(7).

			  Kilobytes transferred per second.

			  Number of seeks per second.

			  Milliseconds per average seek.

			  For multiple lunpaths, data is presented on successive lines for each active lunpath.  If no	lunpaths  were	active,  a
			  blank line is printed.

EXAMPLES

       Show current I/O statistics for all disks:

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

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

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

       Display I/O statistics for all active lunpaths:

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

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

       Display I/O statistics for all active lunpaths every 10 seconds, also show terminal and processor statistics, and terminate after 5 succes-
       sive readings:

WARNINGS

       Users  of 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

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

FILES

SEE ALSO

       vmstat(1), ioscan(1M), intro(7).

																	 iostat(1)