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

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

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

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.

print timestamp, string
instance name to snoop (eg, dad0)
full pathname of file to snoop
mountpoint for filesystem to snoop

# iopattern
# iopattern 10
# iopattern 5 12
# iopattern -m /

percentage of events of a random nature
percentage of events of a sequential nature
number of I/O events
minimum I/O event size
maximum I/O event size
average I/O event size
total kilobytes read during sample
total kilobytes written during sample
device name
mount point
filename (basename) for I/O operation
timestamp, string

Ryan Matteson

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

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

Brendan Gregg [Sydney, Australia]

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

July 25, 2005 version 0.70