HP StorageWorks SAN Virtualization Services Platform Manager User Guide (5697-0454, May 2010)

If no preferred path is set for UDH hosts, VSM distributes virtual disks evenly between DPMs for static
load balancing. The first virtual disk that is assigned permission to the host is presented by the first
DPM. The next virtual disk is presented by the second DPM that supports the configuration. When
you assign host permission to a VDG, all members of the VDG are assigned to use the same DPM.
All subsequent virtual disks assigned permission to the host will be assigned to the other DPM, until
they both service the same number of virtual disks.
Both the preferred path and static load balancing are overridden if you set the primary DPM when
creating a virtual disk or adding host permission to a virtual disk.
NOTE:
You can set a primary DPM for the host for multiple DPM groups by running the Set Preferred Path
wizard multiple times and selecting a different DPM group each time.
To change the preferred path for a host:
1. Right-click the UDH.
2. Select Manage > Manage Preferred Path > Set Preferred Path. The Set preferred path wizard
opens to the Select DPM Group screen.
Figure 33 Set Preferred Path wizard—Select DPM Group screen
.
Since the host is recognized through DPMs, the Set Preferred Path screen enables you to select
the preferred DPM group for the host.
3. Select a DPM group and click Add. The DPM group that you selected is displayed in the lower
area of the screen.
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