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iopattern(1m)                                   USER COMMANDS                                  iopattern(1m)



NAME
       iopattern - print disk I/O pattern. Uses DTrace.

SYNOPSIS
       iopattern [-v] [-d device] [-f filename] [-m mount_point] [interval [count]]

DESCRIPTION
       This  prints  details on the I/O access pattern for the disks, such as percentage of events that were
       of a random or sequential nature.  By default totals for all disks are printed.

       An event is considered random when the heads seek. This program prints the percentage of events  that
       are random. The size of the seek is not measured - it's either random or not.

       Since  this  uses  DTrace,  only the root user or users with the dtrace_kernel privilege can run this
       command.

OPTIONS
       -v     print timestamp, string

       -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,
              # iopattern


       Print 10 second samples,
              # iopattern 10


       Print 12 x 5 second samples,
              # iopattern 5 12


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


FIELDS
       %RAN   percentage of events of a random nature

       %SEQ   percentage of events of a sequential nature

       COUNT  number of I/O events

       MIN    minimum I/O event size

       MAX    maximum I/O event size

       AVG    average I/O event size

       KR     total kilobytes read during sample

       KW     total kilobytes written during sample

       DEVICE device name

       MOUNT  mount point

       FILE   filename (basename) for I/O operation

       TIME   timestamp, string


IDEA
       Ryan Matteson


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
       iopattern 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 0.70                                    Jul 25, 2005                                   iopattern(1m)