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

NAME
     iostat — report I/O statistics

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

DESCRIPTION
     Iostat displays kernel I/O statistics on terminal, disk and cpu opera‐
     tions.

     The options are as follows:

     -c	   Repeat the display count times.  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.

     -M	   Extract values associated with the name list from the specified
	   core instead of the default “/dev/kmem”.

     -N	   Extract the name list from the specified system instead of the
	   default “/vmunix”.

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

     Iostat displays its information in the following format:

     tty
	   tin	   characters read from terminals
	   tout	   characters written to terminals

     disks
	   Disk operations (this field is system dependent).  The header of
	   the field is the disk name and unit number.	If more than four disk
	   drives are configured in the system, iostat displays only the first
	   four drives.	 To force iostat to display specific drives, their
	   names may be supplied on the command line.

	   sps	   sectors transferred per second
	   tps	   transfers per second
	   msps	   milliseconds per average seek (including implied seeks and
		   rotational latency)

     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
     /vmunix	Default kernel namelist.
     /dev/kmem	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.

4th Berkeley Distribution	 June 6, 1993	     4th Berkeley Distribution

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