POWER7 information

MAP 4052

Use this MAP to resolve device bus fabric problems.

Use this MAP to resolve the following problems:

Device bus fabric error (SRN nnnn – 4100)
Temporary device bus fabric error (SRN nnnn – 4101)

The possible causes are:

A failed connection caused by a failing component in the SAS fabric between, and including, the adapter and device enclosure.
A failed connection caused by a failing component within the device enclosure, including the device itself.

Considerations:

Remove power from the system before connecting and disconnecting cables or devices, as appropriate, to prevent hardware damage or erroneous diagnostic results.
Some systems have SAS and PCI-X or PCIe bus interface logic integrated onto the system boards and use a pluggable RAID enablement card (a non-PCI form factor card) for such integrated-logic buses. See the feature comparison tables for PCIe and PCI-X cards. For these configurations, replacement of the RAID enablement card is unlikely to solve a SAS-related problem because the SAS interface logic is on the system board.
Some systems have the disk enclosure or removable media enclosure integrated in the system with no cables. For these configurations, the SAS connections are integrated onto the system boards. A failed connection can be the result of a failed system board or integrated device enclosure.
When using SAS adapters in either an HA two-system RAID or HA single-system RAID configuration, ensure that the actions taken in this MAP are against the primary adapter (not the secondary adapter).
An adapter reset might occur during the system verification step of this procedure. To avoid potential data loss, reconstruct any degraded disk arrays if possible, before performing system verification.

Attention: When SAS fabric problems exist, obtain assistance from your hardware service provider before performing any of the following actions:

Before you replace a RAID adapter: Because the adapter might contain nonvolatile write cache data and configuration data for the attached disk arrays, additional problems can be created by replacing an adapter.
Before you remove functioning disks in a disk array: The disk array might become degraded or failed and additional problems might be created if functioning disks are removed from a disk array.

Step 4052-1

Determine if the problem still exists for the adapter that logged this error by examining the SAS connections as follows:

Start the IBM® SAS Disk Array Manager.
1. Start Diagnostics and select Task Selection on the Function Selection display.
2. Select RAID Array Manager.
3. Select IBM SAS Disk Array Manager.
Select Diagnostics and Recovery Options.
Select Show SAS Controller Physical Resources.
Select Show Fabric Path Graphical View.

Do all expected devices appear in the list and are all paths marked as Operational?

No: Go to Step 4052-2.
Yes: Go to Step 4052-6.

Step 4052-2

Run diagnostics in system verification mode on the adapter to rediscover the devices and connections.

Start Diagnostics and select Task Selection on the Function Selection display.
Select Run Diagnostics.
Select the adapter resource.
Select System Verification.

Note: Disregard any trouble found for now, and continue with the next step.

Step 4052-3

Determine if the problem still exists for the adapter that logged this error by examining the SAS connections as follows:

Start the IBM SAS Disk Array Manager.
1. Start Diagnostics and select Task Selection on the Function Selection display.
2. Select RAID Array Manager.
3. Select IBM SAS Disk Array Manager.
Select Diagnostics and Recovery Options.
Select Show SAS Controller Physical Resources.
Select Show Fabric Path Graphical View.
Select a device with a path that is not Operational (if one exists) to obtain additional details about the full path from the adapter port to the device. See Viewing SAS fabric path information for an example of how this additional detail can be used to help isolate where in the path the problem exists.

Do all expected devices appear in the list and are all paths marked as Operational?

No: Go to Step 4052-4.
Yes: Go to Step 4052-6.

Step 4052-4

Go to SAS fabric identification. Then continue with the next step.

Step 4052-5

Determine if the problem still exists for the adapter that logged this error by examining the SAS connections as follows:

Start the IBM SAS Disk Array Manager.
1. Start Diagnostics and select Task Selection on the Function Selection display.
2. Select RAID Array Manager.
3. Select IBM SAS Disk Array Manager.
Select Diagnostics and Recovery Options.
Select Show SAS Controller Physical Resources.
Select Show Fabric Path Graphical View.
Select a device with a path that is not Operational (if one exists) to obtain additional details about the full path from the adapter port to the device. See Viewing SAS fabric path information for an example of how this additional detail can be used to help isolate where in the path the problem exists.

Do all expected devices appear in the list and are all paths marked as Operational?

No: Go to Step 4052-4.
Yes: Go to Step 4052-6.

Step 4052-6

When the problem is resolved, see the removal and replacement procedures topic for the system unit on which you are working and do the "Verifying the repair" procedure.

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Last updated: Thu, July 23, 2015