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144 Administering dynamic multipathing (DMP)
Administering DMP using vxdmpadm
Gathering and displaying I/O statistics
You can use the vxdmpadm iostat command to gather and display I/O statistics
for a specified DMP node, enclosure, path or controller.
To enable the gathering of statistics, enter this command:
# vxdmpadm iostat start [memory=size]
To reset the I/O counters to zero, use this command:
# vxdmpadm iostat reset
The memory attribute can be used to limit the maximum amount of memory that
is used to record I/O statistics for each CPU. The default limit is 32k (32
kilobytes) per CPU.
To display the accumulated statistics at regular intervals, use the following
command:
# vxdmpadm iostat show {all | dmpnodename=dmp-node | \
enclosure=enclr-name | pathname=path-name | ctlr=ctlr-name} \
[interval=seconds [count=N]]
This command displays I/O statistics for all controllers (all), or for a specified
DMP node, enclosure, path or controller. The statistics displayed are the CPU
usage and amount of memory per CPU used to accumulate statistics, the number
of read and write operations, the number of kilobytes read and written, and the
average time in milliseconds per kilobyte that is read or written.
The interval and count attributes may be used to specify the interval in
seconds between displaying the I/O statistics, and the number of lines to be
displayed. The actual interval may be smaller than the value specified if
insufficient memory is available to record the statistics.
To disable the gathering of statistics, enter this command:
# vxdmpadm iostat stop
Examples of using the vxdmpadm iostat command
The follow is an example session using the vxdmpadm iostat command. The first
command enables the gathering of I/O statistics:
# vxdmpadm iostat start
The next command displays the current statistics including the accumulated
total numbers of read and write operations and kilobytes read and written, on all
paths:
# vxdmpadm iostat show all
cpu usage = 7952us per cpu memory = 8192b
OPERATIONS KBYTES AVG TIME(ms)
PATHNAME READS WRITES READS WRITES READS WRITES
c0t0d0 1088 0 557056 0 0.009542 0.000000
c2t118d0 87 0 44544 0 0.001194 0.000000
c3t118d0 0 0 0 0 0.000000 0.000000
c2t122d0 87 0 44544 0 0.007265 0.000000
c3t122d0 0 0 0 0 0.000000 0.000000