iostat - Reports I/O statistics
iostat [drive...] [interval] [count]
Forces iostat to display specific drives. If drive is not specified
(or the specified drive does not exist on the system or cluster, iostat
displays the first two drives (even if more than two disk drives are
configured in the system).
Causes iostat to report once each interval seconds. The first report
is for all time since the system was last booted, and each subsequent
report is for the last interval only.The value must not be 0.
Specifies the number of reports. For example, iostat 1 10 would pro-
duce 10 reports at 1-second intervals. You cannot specify count
without interval because the first numeric argument to iostat is
assumed to be interval.
The iostat command reports the following information:
+ For terminals (collectively), the number of characters read and writ-
ten per second.
+ For each disk, the number of transfers per second and bytes
transferred per second (in kilobytes).
+ For the system, the percentage of time the system has spent in user
mode, in user mode running low priority (nice) processes, in system
mode, and idling.
To compute this information, iostat counts data transfer completions, the
number of words transferred for each disk, and the collective number of
input and output characters for terminals. Also, each sixtieth of a second,
iostat examines the state of each disk and makes a tally if the disk is
When you issue an iostat command on a cluster member, it displays statis-
tics only for those disks that are local to the member and that member's
usage of those shared disks that it has mounted. It displays 0 for other
disks in the cluster (those it doesn't have mounted), regardless of whether
they are on the shared bus or are local to some other member.
The output from this example displays cpu, terminal, and disk statistics
for the first two disks on the system providing 5 reports at 1 second
# iostat 1 5
tty floppy1 dsk9 cpu
tin tout bps tps bps tps us ni sy id
0 3 0 0 0 0 1 0 4 95
4 58 0 0 0 0 1 0 2 97
1 53 0 0 0 0 0 0 2 98
5 59 0 0 0 0 1 0 1 98
6 60 0 0 0 0 1 0 2 97
The second example specifies device names in the command:
# iostat dsk2 dsk3 cdrom2
tty dsk2 cdrom2 dsk3 cpu
tin tout bps tps bps tps bps tps us ni sy id
0 13 11 5 5 2 2427 1213 0 1 1 98