VERITAS Volume Manager 4.1 Administrator's Guide

Administering Dynamic Multipathing (DMP)

Administering DMP Using vxdmpadm

Chapter 3136

NAME TPDNODENAME PATH-TYPE[-] DMP-NODENAME ENCLR-TYPE ENCLR-NAME

====================================================================================

c7t0d10 emcpower10s2 - emcpower10s2 EMC EMC0

c6t0d10 emcpower10s2 - emcpower10s2 EMC EMC0

Conversely, the next command displays information about the PowerPath node that

corresponds to the path, c7t0d10, discovered by DMP:

# vxdmpadm gettpdnode nodename=c7t0d10

NAME STATE PATHS ENCLR-TYPE ENCLR-NAME

===========================================================

emcpower20s2 ENABLED 2 EMC EMC0

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 or path.

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}

[interval=seconds [count=N]]

This command displays I/O statistics for all controllers (all), or for a speciﬁed DMP node,

enclosure or path. 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

blocks read and written, and the average time in milliseconds per read and write operation.

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