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 users with root privileges 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 ver-
       bose 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)