1 .TH iopattern 1m "$Date:: 2007-08-05 #$" "USER COMMANDS"
3 iopattern \- print disk I/O pattern. Uses DTrace.
6 [\-v] [\-d device] [\-f filename] [\-m mount_point] [interval [count]]
8 This prints details on the I/O access pattern for the disks, such as
9 percentage of events that were of a random or sequential nature.
10 By default totals for all disks are printed.
12 An event is considered random when the heads seek. This program prints
13 the percentage of events that are random. The size of the seek is not
14 measured - it's either random or not.
16 Since this uses DTrace, only the root user or users with the
17 dtrace_kernel privilege can run this command.
21 stable - needs the io provider.
25 print timestamp, string
28 instance name to snoop (eg, dad0)
31 full pathname of file to snoop
34 mountpoint for filesystem to snoop
37 Default output, print I/O summary every 1 second,
42 Print 10 second samples,
48 Print 12 x 5 second samples,
54 Snoop events on the root filesystem only,
62 percentage of events of a random nature
65 percentage of events of a sequential nature
71 minimum I/O event size
74 maximum I/O event size
77 average I/O event size
80 total kilobytes read during sample
83 total kilobytes written during sample
92 filename (basename) for I/O operation
101 See the DTraceToolkit for further documentation under the
102 Docs directory. The DTraceToolkit docs may include full worked
103 examples with verbose descriptions explaining the output.
105 iopattern will run forever until Ctrl\-C is hit, or the
106 specified count is reached.
111 iosnoop(1M), iotop(1M), dtrace(1M)