iostat(1)iostat(1)NAMEiostat - report I/O statistics
SYNOPSIS
[interval [count]]
DESCRIPTION
iteratively reports I/O statistics for each active disk on the system.
Disk data is arranged in a four-column format:
Column Heading Interpretation
──────────────────────────────────────────────────
device Device name
bps Kilobytes transferred per second
sps Number of seeks per second
msps Milliseconds per average seek
If two or more disks are present, data is presented on successive lines
for each disk.
To compute this information, seeks, data transfer completions, and the
number of words transferred are counted for each disk. Also, the state
of each disk is examined times per second (as defined in and a tally is
made if the disk is active. These numbers can be combined with the
transfer rates of each device to determine average seek times for each
device.
With the advent of new disk technologies, such as data striping, where
a single data transfer is spread across several disks, the number of
milliseconds per average seek becomes impossible to compute accurately.
At best it is only an approximation, varying greatly, based on several
dynamic system conditions. For this reason and to maintain backward
compatibility, the milliseconds per average seek field is set to the
value 1.0.
Options
recognizes the following options and command-line arguments:
Report terminal statistics as well as disk (or lunpath) statis‐
tics.
When used with the option, lunpath and terminal sta‐
tistics are displayed. Terminal statistics include:
Number of characters read from terminals.
Number of characters written to terminals.
Percentage of time
system (active processors) has spent in user
mode.
Percentage of time
system (active processors) has spent in user
mode running low-priority (nice) processes.
Percentage of time
system (active processors) has spent in sys‐
tem mode.
Percentage of time
system (active processors) has spent idling.
interval Display successive lines which are summaries of the
last interval seconds. The first line reported is
for the time since a reboot and each subsequent line
is for the last interval only.
count Repeat the statistics count times.
Report active lunpath statistics. When used with the
option, lunpath and terminal statistics are
reported. The lunpaths are not displayed in any
specific order, and the current order may change in
future releases. Lunpath data is arranged in a
four-column format:
symbolic name of the lunpath of the form:
diskm_lunpathn, where m is the instance
number of LUN and n is the instance num‐
ber of lunpath. For example, in
disk47_lunpath7, m is 47 and n is 7.
These instance numbers are displayed by
using the option for the LUN and lunpath
entries. For more information on LUN
and lunpath hardware path, refer to
intro(7).
Kilobytes transferred per second.
Number of seeks per second.
Milliseconds per average seek.
For multiple lunpaths, data is presented on succes‐
sive lines for each active lunpath. If no lunpaths
were active, a blank line is printed.
EXAMPLES
Show current I/O statistics for all disks:
Display I/O statistics for all disks every 10 seconds until INTERRUPT
or QUIT is pressed:
Display I/O statistics for all disks every 10 seconds and terminate
after 5 successive readings:
Display I/O statistics for all disks every 10 seconds, also show termi‐
nal and processor statistics, and terminate after 5 successive read‐
ings:
Display I/O statistics for all active lunpaths:
Display I/O statistics for all active lunpaths every 10 seconds until
INTERRUPT or QUIT is pressed:
Display I/O statistics for all active lunpaths every 10 seconds, and
terminate after 5 successive readings:
Display I/O statistics for all active lunpaths every 10 seconds, also
show terminal and processor statistics, and terminate after 5 succes‐
sive readings:
WARNINGS
Users of must not rely on the exact field widths and spacing of its
output, as these will vary depending on the system, the release of HP-
UX, and the data to be displayed.
AUTHOR
was developed by the University of California, Berkeley, and HP.
FILESSEE ALSOvmstat(1), ioscan(1M), intro(7).
iostat(1)
