Veritas Volume Manager 5.0.1 Administrator's Guide, HP-UX 11i v3, First Edition, November 2009

This policy is useful when the paths in a SAN have unequal
performance, and you want to enforce load balancing manually. You
can assign priorities to each path based on your knowledge of the
configuration and performance characteristics of the available paths,
and of other aspects of your system.
See “Setting the attributes of the paths to an enclosure” on page 172.
In this example, the I/O policy is set to priority for all SENA arrays:
# vxdmpadm setattr arrayname SENA \
iopolicy=priority
priority
This policy shares I/O equally between the paths in a round-robin
sequence. For example, if there are three paths, the first I/O request
would use one path, the second would use a different path, the third
would be sent down the remaining path, the fourth would go down
the first path, and so on. No further configuration is possible as this
policy is automatically managed by DMP.
The next example sets the I/O policy to round-robin for all
Active/Active arrays:
# vxdmpadm setattr arraytype A/A \
iopolicy=round-robin
round-robin
This policy routes I/O down the single active path. This policy can be
configured for A/P arrays with one active path per controller, where
the other paths are used in case of failover. If configured for A/A
arrays, there is no load balancing across the paths, and the alternate
paths are only used to provide high availability (HA). If the current
active path fails, I/O is switched to an alternate active path. No further
configuration is possible as the single active path is selected by DMP.
The following example sets the I/O policy to singleactive for JBOD
disks:
# vxdmpadm setattr arrayname Disk \
iopolicy=singleactive
singleactive
Scheduling I/O on the paths of an Asymmetric Active/Active
array
You can specify the use_all_paths attribute in conjunction with the adaptive,
balanced, minimumq, priority and round-robin I/O policies to specify whether
I/O requests are to be scheduled on the secondary paths in addition to the primary
paths of an Asymmetric Active/Active (A/A-A) array. Depending on the
Administering Dynamic Multipathing
Administering DMP using vxdmpadm
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