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:
- Disconnected or faulty drive cable
- Disconnected minihub canister
- Faulty minihub canister (a separate problem should be reported)
- A failed ESM canister (a separate problem should be reported)
- A removed controller canister on an enclosure containing both controllers and drives
- A drive channel minihub or ESM canister that supports selectable loop speeds set to a speed that is not compatible with other devices on the loop
Caution
Electrostatic discharge can damage sensitive components. Use a grounding wrist strap or other anti-static precautions before removing or handling components.
Important Notes
- Correct this failure as soon as possible. Although the storage subsystem is still operational, a level of path redundancy has been lost. If the remaining drive loop fails, all I/O to that enclosure will fail.
- The Recovery Guru will report separate problems for any enclosures it cannot reach through the channel (loop) of the affected enclosure.
- The Recovery Guru Details area reports the affected enclosure and the working channel over which it can communicate with the enclosure.
- An amber bypass light (In Bypass and Out Bypass) will glow if either the In or Out port is not active in the drive loop.
- The green power light on the ESM canister will be off if the canister is not seated properly.
Recovery Steps
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Fix any other problems reported by the Recovery Guru before attempting to fix this problem. |
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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. |
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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. |
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Trace the cable from the working channel to the ESM canister in the affected drive enclosure reported in the details area.
Caution
Do not disconnect any cables on the working channel. Doing so will cause data loss! |
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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
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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.
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b
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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 loop speed setting switch, verify they are all set to 1 Gb/s. |
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 loop speed setting switch, verify that they all are set to the same speed. Note that if the drive channel minihub or one of the ESM canisters on the loop does not have a loop speed setting switch, all of the other loop speed setting switches on the drive channel loop must be set to 1 Gb/s. |
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If... |
Then... |
There is a connection problem or a loop speed mismatch. |
Correct it and go to step 5. |
There is not a connection problem or loop speed mismatch |
Go to step 6. |
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Select Recheck to rerun 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. |
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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. |
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Select Recheck to rerun 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. |
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