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DESCRIPTION

The options are as follows:

-c

Repeat the display count times. If no wait interval is specified, the default is 1 second.

-C

Display CPU statistics. This is on by default, unless -d is specified.

-d

Display only device statistics. If this flag is turned on, only device statistics will be displayed, unless -C or -T is also specified to enable the display of CPU or TTY statistics.

-D

Display more details. If this flag is turned on, details on read and write statistics will be displayed as MBw/s (Megabyte written per second), MBr/s (Megabyte read per second), rtps (read transactions per second) and wtps (write transactions per second).

-h

Put iostat in ‘top’ mode. In this mode, iostat will show devices in order from highest to lowest bytes per measurement cycle.

-I

Display total statistics for a given time period, rather than average statistics for each second during that time period.

-K

In the blocks transferred display (-o), display block count in kilobytes rather then the device native block size.

-n

Display up to devs number of devices. iostat will display fewer devices if there aren't devs devices present.

-o

Display old-style iostat device statistics. Sectors per second, transfers per second, and milliseconds per seek are displayed. If -I is specified, total blocks/sectors, total transfers, and milliseconds per seek are displayed.

-t

Specify which types of devices to display. There are three different categories of devices:

device type:

da

Direct Access devices

sa

Sequential Access devices

printer

Printers

proc

Processor devices

worm

Write Once Read Multiple devices

cd

CD devices

scanner

Scanner devices

optical

Optical Memory devices

changer

Medium Changer devices

comm

Communication devices

array

Storage Array devices

enclosure

Enclosure Services devices

floppy

Floppy devices

interface:

IDE

Integrated Drive Electronics devices

SCSI

Small Computer System Interface devices

other

Any other device interface

passthrough:

pass

Passthrough devices

The user must specify at least one device type, and may specify at most one device type from each category. Multiple device types in a single device type statement must be separated by commas.

Any number of -t arguments may be specified on the command line. All -t arguments are ORed together to form a matching expression against which all devices in the system are compared. Any device that fully matches any -t argument will be included in the iostat output, up to the number of devices that can be displayed in available columns (80 minimum), or the maximum number of devices specified by the user.

-T

Display TTY statistics. This is on by default, unless -d is specified.

-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

devices

Device operations. The header of the field is the device name and unit number. iostat will display as many devices as will fit in available columns (80 minimum), or the maximum number of devices in the system, whichever is smaller. If -n is specified on the command line, iostat will display the smaller of the requested number of devices, and the maximum number of devices in the system. To force iostat to display specific drives, their names may be supplied on the command line. iostat will not display more devices than will fit in available columns (80 columns minimum), unless the -n argument is given on the command line to specify a maximum number of devices to display. Fewer devices may be displayed.

The standard iostat device display shows the following statistics:

KB/t

kilobytes per transfer

tps

transfers per second

MB/s

megabytes per second

The standard iostat device display, with the -I flag specified, shows the following statistics:

KB/t

kilobytes per transfer

xfrs

total number of transfers

MB

total number of megabytes transferred

The old-style iostat display (using -o) shows the following statistics:

sps

sectors transferred per second

tps

transfers per second

msps

average milliseconds per transaction

The old-style iostat display, with the -I flag specified, shows the following statistics:

blk

total blocks/sectors transferred

xfr

total transfers

msps

average milliseconds per transaction

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

in

% of cpu time in interrupt mode

id

% of cpu time in idle mode