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)