NAME

iostat − Reports I/O statistics

SYNOPSIS

iostat [drive...] [interval] [count]

OPERANDS

drive...
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). 

interval
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. 

count
Specifies the number of reports.  For example, iostat 1 10 would produce 10 reports at 1-second intervals.  You cannot specify count without interval because the first numeric argument to iostat is assumed to be interval. 

DESCRIPTION

The iostat command reports the following information:

       •For terminals (collectively), the number of characters read and written 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 active. 

When you issue an iostat command on a cluster member, it displays statistics 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. 

EXAMPLES

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 intervals:

# 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

SEE ALSO