iopending

iopending(1m)                     USER COMMANDS                    iopending(1m)



NAME
       iopending - plot number of pending disk events. Uses DTrace.

SYNOPSIS
       iopending [-c] [-d device] [-f filename] [-m mount_point] [interval
       [count]]

DESCRIPTION
       This samples the number of disk events that are pending and plots a
       distribution graph. By doing this the "serialness" or "parallelness" of
       disk behaviour can be distinguished.  A high occurance of a pending value
       of more than 1 is an indication of saturation.

       Since this uses DTrace, only users with root privileges can run this
       command.

OPTIONS
       -c     clear screen

       -d device
              instance name to snoop (eg, dad0)

       -f filename
              full pathname of file to snoop

       -m mount_point
              mountpoint for filesystem to snoop

EXAMPLES
       Default output, print I/O summary every 1 second,
              # iopending

       Print 10 second samples,
              # iopending 10

       Print 12 x 5 second samples,
              # iopending 5 12

       Snoop events on the root filesystem only,
              # iopending -m /

FIELDS
       value  number of pending events, 0 == idle

       count  number of samples @ 1000 Hz

       load   1 min load average

       disk_r total disk read Kb for sample

       disk_w total disk write Kb for sample

IDEA
       Dr Rex di Bona

DOCUMENTATION
       See the DTraceToolkit for further documentation under the Docs directory.
       The DTraceToolkit docs may include full worked examples with verbose
       descriptions explaining the output.

EXIT
       iopending will run forever until Ctrl-C is hit, or the specified count is
       reached.

AUTHOR
       Brendan Gregg [Sydney, Australia]

SEE ALSO
       iosnoop(1M), iotop(1M), dtrace(1M)




version 0.60                    November 1, 2005                   iopending(1m)