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

characteristics of the array, the consequent improved load balancing can increase
the total I/O throughput. However, this feature should only be enabled if
recommended by the array vendor. It has no effect for array types other than
A/A-A.
For example, the following command sets the balanced I/O policy with a partition
size of 2048 blocks (2MB) on the enclosure enc0, and allows scheduling of I/O
requests on the secondary paths:
# vxdmpadm setattr enclosure enc0 iopolicy=balanced \
partitionsize=2048 use_all_paths=yes
The default setting for this attribute is use_all_paths=no.
You can display the current setting for use_all_paths for an enclosure, arrayname
or arraytype. To do this, specify the use_all_paths option to the vxdmpadm
gettattr command.
# vxdmpadm getattr enclosure HDS9500-ALUA0 use_all_paths
ENCLR_NAME DEFAULT CURRENT
===========================================
HDS9500-ALUA0 no yes
The use_all_paths attribute only applies to A/A-A arrays. For other arrays, the
above command displays the message:
Attribute is not applicable for this array.
Example of applying load balancing in a SAN
This example describes how to configure load balancing in a SAN environment
where there are multiple primary paths to an Active/Passive device through
several SAN switches. As can be seen in this sample output from the vxdisk list
command, the device c3t2d15 has eight primary paths:
# vxdisk list c3t2d15
Device: c3t2d15
.
.
.
numpaths: 8
c2t0d15 state=enabled type=primary
c2t1d15 state=enabled type=primary
c3t1d15 state=enabled type=primary
179Administering Dynamic Multipathing
Administering DMP using vxdmpadm