displays kernel I/O statistics on terminal,
disk and CPU operations. By default, iostat
displays one line of statistics averaged over the machine's run time. The
to print raw, unaveraged values.
The options are as follows:
- Show CPU statistics. This is enabled by default unless the
-D, -d, or
-T flags are used.
- Repeat the display count
times. Unless the -I flag is in effect, the
first display is for the time since a reboot and each subsequent report is
for the time period since the last display. Unless overridden by the
-w option, the wait interval between lines is
- Show alternate disk statistics. Displays kilobytes
transferred, number of transfers, and time spent in transfers. Use of this
flag disables the default display.
- Show disk statistics. This is the default. Displays
kilobytes per transfer, number of transfers, and megabytes transferred.
Use of this flag disables display of CPU and tty statistics.
- Show the running total values, rather than an average.
- Extract values associated with the name list from the
specified core instead of the default
- Extract the name list from the specified
system instead of the default
- Show tty statistics. This is enabled by default unless the
-C, -D, or
-d flags are used.
- Pause wait seconds between
each display. Unless a count is specified
via the -c option,
iostat will display output until it is
displays its information in the following
- characters read from terminals
- characters written to terminals
- Disk operations. 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.
The alternate display format, (selected with
-D), presents the following values:
- Kilobytes transferred per disk transfer
- Transfers per second
- Megabytes transferred per second
- Kilobytes transferred
- Disk transfers
- Seconds spent in disk activity
- % of CPU time in user mode
- % of CPU time in user mode running niced processes
- % of CPU time in system mode
- % of CPU time processing interrupts
- % of CPU time in idle mode
- default kernel namelist
- default memory file
The sections starting with “Interpreting system activity” in
Installing and Operating 4.3BSD.