Controller Miswire

What Caused the Problem?

A set of drive enclosures (one or more drive enclosures that are on the same loop) has multiple connections to a controller. The Recovery Guru Details area provides specific information you will need as you follow the Recovery Steps.

 Caution: Possible loss of data accessibility. It is very important that you resolve this miswire problem along with any other miswire problem that is reported in the Summary area before attempting to resolve any other problem that is being reported in the Summary area.  Resolving non-miswire problems with miswire problems still present can lead to a loss of data accessibility.

Important Note

This configuration is currently not redundant because a loop of drive enclosures should have one connection to EACH controller. The alternate controller will not be able to access the data on the drives if the connected controller fails.

Recovery Steps

1 Use the information provided in the Recovery Guru Details area to determine which drive expansion ports are miswired.

Note: Select the Storage Subsystem >> View >> Connections menu option for a table of the connections between the controller and the drive enclosures.

Trace the cables from the controller enclosure's miswired drive channel connections to the connected ESM canister. Follow the cable paths until you find a connection where two different drive ports from the same controller are connected to the same set of drive enclosures (one or more drive enclosures that are on the same loop) .

The following example shows a common miswire configuration:

1. Controller enclosure
2. Drive enclosure

In the example above, two drive ports from the same controller are connected to both ESM canisters in the same drive enclosure. If you lose access to this controller, then you will also lose access to this drive enclosure.  This problem can also happen when multiple drive enclosures are looped together.

2 Reconnect the cables so that each path in the drive loop is connected to a different controller. Use the interface cable routing examples in the Hardware Cabling Guide as a reference for correct cabling.

The following example shows the corrected cable configuration from the previous example.

1. Controller enclosure
2. Drive enclosure

In the corrected configuration, if you lose access to one of the controllers, you will still have access to the drive enclosure through the alternate controller.

3 Click the Recheck button to rerun the Recovery Guru. The failure should no longer appear in the Summary area. If the failure appears again, contact your technical support representative.