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

NAME

iostat -- report I/O statistics

SYNOPSIS

iostat [-CdhKIoT] [-c count] [-n devs] [-t type,if,pass] [-w wait] [drives]

DESCRIPTION

Iostat displays kernel I/O statistics on terminal, device and cpu opera- tions. 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 speci- fied. -d Display only device statistics. If this flag is turned on, only device statistics will be displayed, unless -C or -T is also speci- fied 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 transac- tions 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 aver- age 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 mil- liseconds per seek are displayed. -t Specify which types of devices to display. There are three differ- ent 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 80 columns, or the maximum number of devices specified by the user. -T Display TTY statistics. This is on by default, unless -d is speci- fied. -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 a standard 80 column screen, 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 an 80 column screen, unless the -n argument is given on the command line to specify a maximum number of devices to display. If fewer devices are specified on the command line than will fit in an 80 column screen, iostat will show only the specified devices. 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 statis- tics: 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

EXAMPLES

iostat -w 1 da0 da1 cd0 Display statistics for the first two Direct Access devices and the first CDROM device every second ad infinitum. iostat -c 2 Display the statistics for the first four devices in the system twice, with a one second display interval. iostat -t da -t cd -w 1 Display statistics for all CDROM and Direct Access devices every second ad infinitum. iostat -t da,scsi,pass -t cd,scsi,pass Display statistics once for all SCSI passthrough devices that provide access to either Direct Access or CDROM devices. iostat -h -n 8 -w 1 Display up to 8 devices with the most I/O every second ad infinitum. iostat -dh -t da -w 1 Omit the TTY and CPU displays, show devices in order of performance and show only Direct Access devices every second ad infinitum. iostat -Iw 3 Display total statistics every three seconds ad infinitum. iostat -odICTw 2 -c 9 Display total statistics using the old-style output format 9 times, with a two second interval between each measurement/display. The -d flag gen- erally disables the TTY and CPU displays, but since the -T and -C flags are given, the TTY and CPU displays will be displayed.

SEE ALSO

fstat(1), netstat(1), nfsstat(1), ps(1), systat(1), pstat(8), vmstat(8) The sections starting with ``Interpreting system activity'' in Installing and Operating 4.3BSD.

HISTORY

This version of iostat first appeared in FreeBSD 3.0.

AUTHORS

Kenneth Merry <ken@FreeBSD.org> DragonFly 3.9 December 22, 1997 DragonFly 3.9