Managing High Availability; Array Dual Pathing; Load Balancing; Lun Path Failover - HP StorageWorks 12000 - Virtual Library System EVA Gateway User Manual

NOTE:
The password can also be changed from the VLS CLI. See

Managing High Availability

This section describes the methods to maintain high availability with your VLS.

Array Dual Pathing

The VLS12000 Gateway supports dual pathing to the Gateway arrays, which provides path balancing
and transparent path failover on the VLS. Having followed the setup recommendations in the HP
StorageWorks VLS12000 Gateway virtual tape libraries solutions guide and the installation instructions
in this guide, each node on the VLS is connected to two fabrics/zones which are each connected to
the Gateway arrays by two or more paths. This assures that the VLS can establish two paths per LUN,
each path on a separate fabric/zone.

Load Balancing

For load balancing, half of the data transfer (from a specific node through a fabric to the array) is
conducted over one path; half over a second fabric, hence another path. The paths are selected as
follows: Once configured, the device recognizes all paths to each node on the device. From all
potential preferred paths and all potential secondary paths (see
one preferred path and one secondary path.
NOTE:
During each reboot the device is re-analyzed and the preferred and secondary paths are reassigned.
To view the preferred path for each LUN in the Storage LUN Details:
1. In Command View VLS, select the System tab.
2. Select Storage LUNs in the navigation tree.
3. Select the View button for either All LUNs or the LUNs in the desired <Storage Pool #>.
Summary information displays at the top of the list. Preferred and secondary paths are listed after
the summary information in the Storage LUN Details Per Node sections.
NOTE:
It may take several minutes to display this information if there are many LUNs.

LUN Path Failover

LUN path failover allows the VLS12000 to automatically reroute data traffic usually assigned to one
(preferred) path to another (secondary) path when the preferred path fails. Path status is shown in
Command View VLS under Storage LUN Details.
144 Management
CLI Management commands.
Step 3 on page 39), the array assigns