Copyright (c) 1985, 1991 The Regents of the University of California.
All rights reserved.

%sccs.include.redist.roff%

@(#)iostat.8 6.8 (Berkeley) 04/24/91

C 4 iostat - report I/O statistics

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

Iostat reports certain kernel statistics kept about terminal, disk and cpu activity.

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

/vmunix default kernel namelist

/dev/kmem default memory file

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" .