Logical Drive Not On Preferred Path

What Caused the Problem?

There is a problem accessing the controller listed in the Recovery Guru Details Area. Any logical drives that have this controller assigned as their preferred path will be moved to the non-preferred path (alternate controller). This procedure will help you pinpoint the problem along the data path. Because the logical drives will be moved to the alternate controller, they should still be accessible. Therefore, no action is required on the individual logical drives.

Possible causes include:

The Recovery Guru Details area provides specific information you will need as you follow the recovery steps.

Caution
Do not replace the controller until you are instructed to do so. This procedure will instruct you to check the components along the connection, check the host adapters, and eventually instruct you to replace the controller, if necessary.

Caution
Electrostatic discharge can damage sensitive components. Use a grounding wrist strap or other anti-static precautions before removing or handling components.

Important Notes

When Auto Logical Drive Transfer (ADT) is enabled, it can take several minutes for the host-based, multi-path failover driver to recognize a restored or modified preferred path. A Logical Drive Not On Preferred Path error will be reported during this time. If you have recently modified the preferred path using the Array>>Change>>Ownership/Preferred Path or Logical Drive>>Change>>Ownership/Preferred Path menu options or performed a recovery procedure that has restored a preferred path, wait at least 10 minutes and run the Recovery Guru again using the Recheck button. If this error is reported again, perform the recovery procedures listed below.

Use the Storage Subsystem Profile to determine whether you have ADT enabled on a mapped host. Select the View>>Storage Subsystem Profile menu option from the Subsystem Management Window and then select the profile's Mappings tab. Determine the host types of all mapped hosts using the Logical Drive-to-LUN Mappings and Topology sections. Then, find the host type's ADT enabled status by using the NVSRAM Host Type Internal Definitions section.

Recovery Steps

1

If...

Then...

The controller was NOT manually taken Offline

Go to Step 2.

The controller was manually taken Offline

Place the controller back Online by highlighting the controller in the Physical View of the Subsystem Management Window and selecting Controller>>Place>>Online.

Then, go to Step 8.

2

Check the following components on both ends of the connection for loose connections or visible damage:

  • External cables
  • Hubs and switches

If...

Then...

The connection components are OK

Go to Step 3.

There is a problem with the connection

Fix the connection problem. Then, go to Step 7.

3

Use the information in the following table to determine the action to take.

If...

Then...

The host connected to this storage subsystem is NOT connected to any other storage subsystems

Verify that its host adapter is operational.

  • If the host adapter is operational, the controller in the storage subsystem is probably defective. Go to Step 4.
  • If the host adapter is defective, correct the problem, then go to Step 7.

The host connected to this storage subsystem is connected to other storage subsystems

Check the Enterprise Management Window for storage subsystems showing a Needs Attention status.

  • If one or more storage subsystems connected to this host/host adapter does not have a Needs Attention status, then the controller in the storage subsystem is probably defective. Go to Step 4.
  • If every storage subsystem connected to this host/host adapter has a Needs Attention status, then the associated host adapter is probably defective. Fix the host adapter problem, then go to Step 7.

4

Remove the defective controller. The defective controller is listed in the Recovery Guru Details area.

Note: Before you insert a new controller canister into a Directly Managed Storage Subsystem (refer to the Network Management Type column in the Enterprise Management Window), you must update the DHCP/BOOTP server so that it will associate the new controller's hardware Ethernet address with the host name and IP address previously assigned to the removed controller.

To update the DHCP/BOOTP server, find the entry associated with the removed controller and replace its Ethernet address with the new controller's Ethernet address. The controller's Ethernet address is located on an Ethernet ID label on the controller canister in the form xx.xx.xx.xx.xx.xx. If you need more details, consult the Storage System Planning Guide.

5

Make sure at least 1 minute has elapsed; then, insert the new controller canister firmly into place.

6

If...

Then...

The controllers for this storage subsystem are located in an enclosure containing only controllers

Go to Step 7.

The controllers for this storage subsystem are located in an enclosure containing both controllers and drives

The new controller's cache battery age must be reset. To reset the battery age, select the Components button on the enclosure containing the controllers in the Physical View of the Subsystem Management Window. Highlight the Batteries option and select the Reset button associated with the new controller canister.

Go to Step 7.

7

If...

Then...

The controller is NOT Offline

Go to Step 8.

The controller is Offline

Place the controller Online by highlighting the controller in the Physical View of the Subsystem Management Window and selecting Controller>>Place>>Online.

Go to Step 8.

8

If you have logical drives mapped to hosts that have Automatic Logical Drive Transfer (ADT) disabled, it may be necessary to redistribute the logical drives to their preferred controller. Use the following steps to determine the ADT status of the hosts connected to your storage subsystem:

a

Open the Storage Subsystem Profile by selecting the View>>Storage Subsystem Profile menu option from the Subsystem Management Window. Then, select the profile's Mappings tab.

b

Scroll to the NVSRAM Host Type Internal Definitions section.

c

If...

Then...

There are hosts mapped to logical drives on this storage subsystem that have an ADT status of disabled

OR

There are hosts mapped to logical drives on this storage subsystem that are not running a host-based, multi-path failover driver

It may be necessary to redistribute the logical drives to their preferred controller. If the Subsystem Management Window's Storage Subsystem>>Redistribute Logical Drives menu option is visible, select the option.

Note: If you have a mix of hosts with ADT enabled and ADT disabled, all logical drives will be immediately assigned back to their preferred path. However, until the host-based, multi-path failover driver detects the valid preferred path (may take several minutes), the logical drives mapped to the ADT-enabled hosts may get temporarily returned back to the non-preferred path.

If the menu option is not visible, the logical drives are already associated with their preferred controllers and no action is needed.

Go to Step 9.

There are NO hosts mapped to logical drives on this storage subsystem with an ADT status of disabled

AND

All hosts mapped to logical drives on this storage subsystem are running a host-based, multi-path failover driver

No action is required.

If logical drives need to be redistributed to their preferred controller, the host-based, multi-path failover driver will automatically initiate the transfer.

Note that detection of a restored preferred path by the multi-path failover driver can take several minutes.

Go to Step 9.

9

Note: When Auto Logical Drive Transfer (ADT) is enabled, it can take several minutes for the host-based, multi-path failover driver to recognize a restored preferred path. Wait at least 10 minutes before selecting Recheck to ensure the failure has been fixed. Use the Storage Subsystem Profile to determine whether you have ADT enabled on a mapped host. Select the View>>Storage Subsystem Profile menu option from the Subsystem Management Window and then select the profile's Mappings tab. Determine the host types of all mapped hosts using the Logical Drive-to-LUN Mappings and Topology sections. Then, find the host type's ADT enabled status by using the NVSRAM Host Type Internal Definitions section.

Select Recheck to rerun the Recovery Guru to ensure that the failure has been fixed.

If...

Then...

Another type of failure is reported

Follow the recovery procedures given for that failure.

No failures are reported

You are finished with the recovery procedure.

Note: If you replaced the controller and the file systems/logical drives do not respond, reboot your host.