DKSTAT(1) DKSTAT(1)
NAME
dkstat - report disk I/O statistics
SYNOPSIS
dkstat [-h host] [-L] [-f {r|t|s}] [-r] [-w] [-n ndisks] [-c] [-a] [-i
devspec[,devspec ...]] [-x devspec[,devspec ...]] [interval [repeat]]
TYPICAL USAGE
To monitor I/O rates on all disks every 5 seconds
dkstat
To continuously display a table of disks on the host "babylon", use the
following command;
dkstat -c -ft -h babylon
DESCRIPTION
dkstat reports physical disk I/O statistics. The default report shows
the average physical I/O rate (requests per second, or IOPS) to each disk
during the sample interval (default 5 seconds).
The options to dkstat are as follows;
-? Output usage information.
-h host
Report for the host host, which must be running pmcd(1). The
default is to report for the local host.
-L Report for the local host and by-pass pmcd(1). This option is
mutually exclusive with the -h option and is the default if pmcd(1)
is not running.
-c Invokes continuous mode, using a curses(3) display. This is most
useful with the "sorted" (-fs) and "table" (-ft) display formats.
-f {r|t|s}
Selects the report format as follows:
-fr selects ``row'' format (one column per drive). The report is
sorted on drive name across the page. This is the default
display format.
-ft selects ``table'' format (one line per controller). The report
is sorted on controller name down the page and by drive unit
number across the page.
For SCSI devices with non-zero Logical Unit Numbers (LUNs) all
devices for a single SCSI target address appear in a the same
row, sorted by LUN. Down the page, rows are sorted by SCSI
target within controller.
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-fs selects ``sorted'' format (one drive per line). The report is
sorted for the most active drive, depending on the -r and -w
flags. If neither -r or -w are given, the report is sorted on
total number of I/Os (reads plus writes). The -n option
restricts the report to the ndisks most active disks (default
22). The %Busy column in the output is the percentage of time
during the interval that the drive was active. The MeanST
column in the output is the average service time of all
requests which completed during the interval (in units of
milliseconds).
-r Only report reads from each drive. The default is to sum reads and
writes. The -fs style report will be sorted for the drives which
perform the most read I/Os per second.
-w Only report writes to each drive. The -fs style report will be
sorted for the drives which perform the most write I/Os per second.
-rw Report both reads and writes to each drive. If neither -r or -w are
given, then report total I/Os (reads plus writes).
interval [repeats]
Specifies the interval in seconds between successive reports
(default 5 seconds) and the number of intervals to report (default
is to repeat forever). All statistics are averaged over the
interval.
DEVICE SELECTION
The -a flag (default) causes all drives and controllers to be reported
(depending on the report format). This may be modified by the -i option
to include only some drives and exclude all others, or by the -x option
to exclude some drives and include all others.
The argument to the -i or -x option is a comma separated list (without
spaces before or after each comma) of device specifiers (devspec). A
devspec is a string of characters that might reasonably be expected to be
the prefix for the names (as report via -I) of one or more devices.
Examples;
dks1d6l3 SCSI controller 1, target 6, LUN 3.
dks0d1 SCSI controller 0, target 1, all LUNs.
dks4 All drives on SCSI controller 4.
dks6,dks0d3 All drives on SCSI controller 6 and SCSI target 3 on SCSI
controller 0.
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SEE ALSO
pmcd(1), sar(1), sadc(1), grtop(1), osview(1) and grosview(1).
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