IOSTAT(1) UNIX Programmer's Manual IOSTAT(1)
iostat - report I/O statistics
S
\bSY
\bYN
\bNO
\bOP
\bPS
\bSI
\bIS
\bS
i
\bio
\bos
\bst
\bta
\bat
\bt [ drives ] [ interval [ count ] ]
D
\bDE
\bES
\bSC
\bCR
\bRI
\bIP
\bPT
\bTI
\bIO
\bON
\bN
_
\bI_
\bo_
\bs_
\bt_
\ba_
\bt iteratively reports the number of characters read and
written to terminals per second, and, for each disk, the
number of transfers per second, kilobytes transferred per
second, and the milliseconds per average seek. It also
gives the percentage of time the system has spent in user
mode, in user mode running low priority (niced) processes,
in system mode, and idling.
To compute this information, for each disk, seeks and data
transfer completions and number of words transferred are
counted; for terminals collectively, the number of input and
output characters are counted. Also, each sixtieth of a
second, the state of each disk is examined and a tally is
made if the disk is active. From these numbers and given
the transfer rates of the devices it is possible to deter-
mine average seek times for each device.
The optional _
\bi_
\bn_
\bt_
\be_
\br_
\bv_
\ba_
\bl argument causes _
\bi_
\bo_
\bs_
\bt_
\ba_
\bt to report once
each _
\bi_
\bn_
\bt_
\be_
\br_
\bv_
\ba_
\bl seconds. The first report is for all time
since a reboot and each subsequent report is for the last
The optional _
\bc_
\bo_
\bu_
\bn_
\bt argument restricts the number of reports.
If more than 4 disk drives are configured in the system,
_
\bi_
\bo_
\bs_
\bt_
\ba_
\bt displays only the first 4 drives, with priority given
to Massbus disk drives (i.e. if both Unibus and Massbus
drives are present and the total number of drives exceeds 4,
then some number of Unibus drives will not be displayed in
favor of the Massbus drives). To force _
\bi_
\bo_
\bs_
\bt_
\ba_
\bt to display
specific drives, their names may be supplied on the command
S
\bSE
\bEE
\bE A
\bAL
\bLS
\bSO
\bO
Printed 7/9/88 April 29, 1985 1
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