HP 12000 HP StorageWorks 12000 Gateway Virtual Library System User Guide (AH81 - Page 142

Load Balancing, LUN Path Failover, In Command View VLS, select the System tab.

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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 Step 3 on page 39), the array assigns 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 . 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. A failover is indicated in the Storage LUN Details screen by the yellow warning icon and the notification message: Fibre Channel Path Failed Over to {#:#:#:#}. The #s stand for the node port; bus number (always 0); the target id (an array port); and the LUN number on the array. When one path fails, automatic failover reroutes data traffic to the secondary path so the data transfer still happens, but potentially at a slower rate. It is advised that you restore the path as soon as possible to avoid a double path failure. To restore the failed path: 1. Determine the cause of the failure and repair it if needed. 2. In Command View VLS, access the System tab. 3. Select Storage LUNs from the navigation tree. 4. Select View to display the storage LUN details. 5. Select Fix Primary Paths from the task bar to display the Fix Primary Paths Wizard. 6. Select Apply to set all paths back to their primary paths. Failure of both paths (double path failure) is indicated by the red critical icon and a specific notification message. The notification message differs based on whether the failure occurs while running or upon booting the system. • A double path failure that occurs while running results in the critical alert Fibre Channel Paths Failed for Lun, ulid wwnn . 142 Management

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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
Step 3
on page 39), the array assigns
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
.
A failover is indicated in the
Storage LUN Details
screen by the yellow warning icon and the notification
message:
Fibre Channel Path Failed Over to {#:#:#:#}
. The #s stand for the node port; bus number
(always 0); the target id (an array port); and the LUN number on the array.
When one path fails, automatic failover reroutes data traffic to the secondary path so the data transfer
still happens, but potentially at a slower rate. It is advised that you restore the path as soon as possible
to avoid a double path failure.
To restore the failed path:
1.
Determine the cause of the failure and repair it if needed.
2.
In Command View VLS, access the System tab.
3.
Select
Storage LUNs
from the navigation tree.
4.
Select
View
to display the storage LUN details.
5.
Select
Fix Primary Paths
from the task bar to display the
Fix Primary Paths Wizard
.
6.
Select
Apply
to set all paths back to their primary paths.
Failure of both paths (double path failure) is indicated by the red critical icon and a specific notification
message. The notification message differs based on whether the failure occurs while running or upon
booting the system.
•
A double path failure that occurs while running results in the critical alert
Fibre Channel Paths
Failed for Lun, ulid <numerical LUN id number> wwnn <numerical wwnn>
.
Management
142