Drive Enclosure - Loss of Path Redundancy

What Caused the Problem?

An enclosure with redundant drive loops (channels) has lost communication through one of its loops. The enclosure has only one loop available for I/O. The Recovery Guru Details area provides specific information you will need as you follow the recovery steps.

Loss of path redundancy can result from any of the following:

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

Important Notes

Recovery Steps

1

Fix any other problems reported by the Recovery Guru before attempting to fix this problem.

2

If...

Then...

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

If...

Then...

One of the controller canisters is removed

Reinsert the controller.

Go to Step 7.

Both controller canisters are present

To locate the non-working channel, start with the controller canister that is associated with the working channel. Looking at the controller canisters from the back of the enclosure, Controller A is the left controller canister and is associated with channel 1. Controller B is the right controller canister and is associated with channel 2.

Go to Step 3.

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

To locate the non-working channel, start with the drive minihub in the controller enclosure that corresponds to the working channel (refer to the labels on the back of the controller enclosure if needed).

Go to Step 3.

3

Trace the cable from the working channel to the ESM canister in the affected drive enclosure reported in the Recovery Guru Details area.

Caution
Do not disconnect any cables on the working channel. Doing so will cause data loss!

4

Locate the other ESM canister in the affected drive enclosure and trace the cables back to the minihub on a controller enclosure or the controller canister for the combination controller/drive enclosure. This is the non-working channel. When tracing the cables on the non-working channel, perform the following:

a

Check for loose or damaged cables. An amber loop bypass light (In Bypass or Out Bypass) will be lit if there is a connection problem between two enclosures.

b

Check for a loop data rate mismatch.

If...

Then...

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

Look at the ESM canisters on the non-working channel. If any of the ESM canisters have a switch to set the loop data rate, use the View>>Storage Subsystem Profile option and select the Enclosure tab to verify they are all set to the maximum data rate (1 Gbps or 2 Gbps).

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

If the ESM canisters or drive channel minihub on the non-working channel has a switch to set the loop data rate, verify that they all are set to the same data rate (1 Gbps or 2 Gbps). Note that if the drive channel minihub or one of the ESM canisters on the loop does not have a switch to set the loop speed setting switch, all of the other data rate switches on the drive channel loop must be set to 1 Gbps.

If...

Then...

There is a connection problem or a loop data rate mismatch

Correct it and go to step 5.

There is not a connection problem or loop data rate mismatch

Go to step 6.

5

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

If...

Then...

The problem has been fixed

You are finished with this procedure.

The problem has not been fixed

Go to step 6.

6

Check the green power light on each ESM canister along the non-working channel. If it is off, reseat the canister by removing it from the drive enclosure and waiting 10 seconds. Re-insert the canister firmly, then go to step 7.

7

Wait 40 seconds, then select Recheck to rerun the Recovery Guru to ensure that the problem has been fixed.

If...

Then...

The problem has been fixed

You are finished with this procedure.

The problem has not been fixed

Contact your technical support representative.