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

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

SYNOPSIS
       iiooppaatttteerrnn  [-v]  [-d  device]  [-f filename] [-m mountpoint] [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
       dtracekernel privilege can run this command.

OOPPTTIIOONNSS
       -v     print timestamp, string

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

       -f filename
              full pathname of file to snoop

       -m mountpoint
              mountpoint for filesystem to snoop

EEXXAAMMPPLLEESS
       Default output, print I/O summary every 1 second,
              # iiooppaatttteerrnn


       Print 10 second samples,
              # iiooppaatttteerrnn 10


       Print 12 x 5 second samples,
              # iiooppaatttteerrnn 5 12


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


FFIIEELLDDSS
       %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


IIDDEEAA
       Ryan Matteson


DDOOCCUUMMEENNTTAATTIIOONN
       See  the  DTraceToolkit for further documentation under the Docs direc-
       tory. The DTraceToolkit docs may include full worked examples with ver-
       bose descriptions explaining the output.

EEXXIITT
       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)