.TH iopattern 1m "Jul 25, 2005" "version 0.70" "USER COMMANDS" .SH NAME iopattern \- print disk I/O pattern. Uses DTrace. .SH SYNOPSIS .B iopattern [\-v] [\-d device] [\-f filename] [\-m mount_point] [interval [count]] .SH 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. .SH OPTIONS .TP \-v print timestamp, string .TP \-d device instance name to snoop (eg, dad0) .TP \-f filename full pathname of file to snoop .TP \-m mount_point mountpoint for filesystem to snoop .SH EXAMPLES .TP Default output, print I/O summary every 1 second, # .B iopattern .PP .TP Print 10 second samples, # .B iopattern 10 .PP .TP Print 12 x 5 second samples, # .B iopattern 5 12 .PP .TP Snoop events on the root filesystem only, # .B iopattern \-m / .PP .SH FIELDS .TP %RAN percentage of events of a random nature .TP %SEQ percentage of events of a sequential nature .TP COUNT number of I/O events .TP MIN minimum I/O event size .TP MAX maximum I/O event size .TP AVG average I/O event size .TP KR total kilobytes read during sample .TP KW total kilobytes written during sample .TP DEVICE device name .TP MOUNT mount point .TP FILE filename (basename) for I/O operation .TP TIME timestamp, string .PP .SH IDEA Ryan Matteson .PP .SH DOCUMENTATION See the DTraceToolkit for further documentation under the Docs directory. The DTraceToolkit docs may include full worked examples with verbose descriptions explaining the output. .SH EXIT iopattern will run forever until Ctrl\-C is hit, or the specified count is reached. .SH AUTHOR Brendan Gregg [Sydney, Australia] .SH SEE ALSO iosnoop(1M), iotop(1M), dtrace(1M)