Content-type: text/html Man page of iostat

iostat

Section: User Commands (1)
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NAME

iostat - Reports I/O statistics  

SYNOPSIS

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


 

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, bytes transferred per second (in kilobytes), and the milliseconds per average seek. Not all disk drives report seek times. 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 the number of seeks and 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. From these numbers and given the transfer rates of the devices, it is possible to determine the average seek times for each device.
 

OPERANDS

Forces iostat to display specific drives. If drive is not specified, iostat displays the first four drives (even if more than four disk drives are configured in the system). Causes iostat to report once each interval seconds. The first report is for all time since a reboot, and each subsequent report is for the last interval only. 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.

If a disk drive is attached and configured but has never been accessed, iostat displays the disk name as dkn, where n is the drive number of the console name for the drive. For example, if dka500 is the console name of the never accessed disk, the name iostat uses is dk500.
 

EXAMPLES

The output from this example displays cpu, terminal, and disk statistics for the first four disks on the system providing 5 reports in 1 second intervals.

# iostat 1 5
      tty     rz1      rz2      rz3      rz4     cpu
 tin tout bps tps  bps tps  bps tps  bps tps  us ni sy id
   1   52   2   0    1   0   13   1    4   1   8  0  9 83
   1   16   7   1    2   0    5   2    2   0   3  0 10 87
   0    0   0   0    0   0    0   0    0   0   0  0  1 98
   2    2   2   1    0   0   50   6    0   0   9  0  9 82
   1  191   2   1    0   0   47   6    0   0   8  0  9 83

Note that this example does not show the average seek times (msps) for the disk drives. Not all disk drives report seek time.
 

SEE ALSO

Commands:  vmstat(1)


 

Index

NAME
SYNOPSIS
DESCRIPTION
OPERANDS
EXAMPLES
SEE ALSO

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Time: 02:42:46 GMT, October 02, 2010