MAP 0050: SCSI bus problems

Purpose of this MAP

Use this MAP to analyze problems with a SCSI bus.

Considerations

• To prevent hardware damage or erroneous diagnostic results from a system with its power turned on, use "PCI hot-plug manager" subtask "replace/remove PCI hot plug adapter" before connecting or disconnecting cables or devices.
• Also, use this MAP for SCSI adapters that are built into system backplanes or I/O backplanes. If this procedure calls for replacing a SCSI adapter and the SCSI adapter is built into the system backplane or I/O backplane, replace the system backplane or I/O backplane as appropriate.
• If the failure is a terminator power failure (SRNs xxx-226, xxx-240, xxx-800), always allow five minutes for the PTC to cool.
• The differential version of the adapter has socket-type terminators to support high-availability. If this is the adapter's configuration, the terminators would have been removed from the adapter. MAP steps requiring the removal of the cable from the adapter do not apply, because an adapter that is not terminated always fails diagnostics. Proper SCSI diagnostics require proper termination. If the configuration involves a Y-cable, leave it, with the appropriate terminator, attached to the adapter. Or, place an external differential terminator on the external port.
• If the system uses shared disk-drive hardware or a high-availability configuration, ensure that the other system that is sharing the devices is not using the devices. For additional information concerning high-availability configurations, see SCSI service hints.
• For intermittent problems that cannot be resolved with this MAP, refer to SCSI service hints.
• If the SCSI bus is attached to a RAID subsystem, refer to the RAID subsystem documentation for any problem determination. If the RAID adapter is a PCI-X RAID adapter, refer to the PCI-X SCSI RAID Controller Reference Guide for AIX.

• Step 0050-1
  Have changes been made recently to the SCSI configuration?

  NO

  Go to Step 0050-2.

  YES

  Go to Step 0050-5.

• Step 0050-2

  Are there any hot-swap devices (SCSI disk drives or media devices) controlled by the adapter?

  NO

  Go to Step 0050-3.

  YES

  Go to Step 0050-11.

• Step 0050-3
  Are there any devices other than hot-swappable devices controlled by the adapter?

  NO

  Go to Step 0050-4.

  YES

  Go to Step 0050-13.

• Step 0050-4
  Is an enclosure or drawer that supports hot-swap devices controlled by the adapter?

  NO

  Go to Step 0050-22.

  YES

  Go to Step 0050-15.

• Step 0050-5

  This step handles cases where recent changes have been made to the SCSI configuration.

  Using the first three digits of the SRN, refer to the FFC listing and determine if the adapter is single-ended or differential.

  Is the adapter a single-ended adapter?

  NO

  Go to Step 0050-6.

  YES

  Go to Step 0050-7.

• Step 0050-6

  The adapter's termination jumper settings may be incorrect. Power off the system, and inspect jumper J7.

  Are the jumpers correct?

  NO

  Go to Step 0050-8.

  YES

  Go to Step 0050-9.

• Step 0050-7

  If the adapter is not being used in a high-availability configuration, be sure sockets RN1, RN2, and RN3 are populated.

  If the adapter is being used in a high-availability configuration, be sure sockets RN1, RN2, and RN3 are not populated.

  Go to Step 0050-9.

• Step 0050-8
  1. Correct the jumper settings and reinstall the adapter and all cables.
  2. Power on the system, and run diagnostics in system verification mode on the adapter.
  Did the diagnostic pass?

  NO

  Go to Step 0050-9.

  YES

  Go to Step 0050-10.

• Step 0050-9
  Check for the following problems:

  • Address conflicts between devices.
  • Cabling problems such as configurations that exceed the maximum cable lengths, missing termination, or excessive termination.
  Did you find a problem?

  NO

  Go to Step 0050-2.

  YES

  Go to Step 0050-10.

• Step 0050-10
  1. Correct the problem.
  2. Power on the system, and run diagnostics in system verification mode on the adapter.
  Did a failure occur?

  NO

  Go to Verify a repair.

  YES

  Go to Step 0050-2.

• Step 0050-11

  This step determines if a hot-swap device is causing the failure.

  1. Go to Preparing for hot-plug SCSI device or cable deconfiguration.
  2. Disconnect all hot-swap devices attached to the adapter.
  3. Go to After hot-plug SCSI device or cable deconfiguration.
  4. If the Missing Options menu displays, select the option The resource has been turned off, but should remain in the system configuration for all the devices that were disconnected.
  5. Run the diagnostics in system verification mode on the adapter.

  Did a failure occur?

  NO

  Go to Step 0050-12.

  YES

  Go to Step 0050-3.

• Step 0050-12

  Go to Preparing for hot-plug SCSI device or cable deconfiguration. Reconnect the hot-plug devices one at a time. After reconnecting each device, do the follow:

  1. Go to After hot-plug SCSI device or cable deconfiguration.
  2. Rerun the diagnostics on the adapter.
  3. If the adapter fails, the problem may be with the last device reconnected. Perform these substeps:
     1. Follow repair procedures for that last device.
     2. Rerun diagnostics on the adapter.
     3. If diagnostics fail, replace the SES backplane corresponding to the slot for the device.
     4. Rerun diagnostics.
     5. If diagnostics fail, replace the last device.
     6. Rerun diagnostics on the adapter.
     7. If diagnostics pass, go to Verify a repair. Otherwise, contact your support center.
        Note: A device problem can cause other devices attached to the same SCSI adapter to go into the defined state. Ask the system administrator to make sure that all devices attached to the same SCSI adapter as the device that you replaced are in the available state.
  4. If no errors occur, the problem could be intermittent. Make a record of the problem. Running the diagnostics for each device on the bus may provide additional information.
• Step 0050-13

  This step determines if a device other than a hot-swappable device is causing the failure. Follow these steps:

  1. Go to Preparing for hot-plug SCSI device or cable deconfiguration.
  2. Disconnect all devices attached to the adapter (except for the device from which you boot to run diagnostics; you may want to temporarily move this device to another SCSI port while you are trying to find the problem).
  3. Go to After hot-plug SCSI device or cable deconfiguration.
  4. If the Missing Options menu displays, select the option The resource has been turned off, but should remain in the system configuration for all the devices that were disconnected.
  5. Run the diagnostics in system verification mode on the adapter.
  Did a failure occur?

  NO

  Go to Step 0050-14.

  YES

  Go to Step 0050-4.

• Step 0050-14

  Reconnect the devices one at time. After reconnecting each device, follow this procedure:

  1. Rerun the diagnostics in system verification mode on the adapter.
  2. If there is a failure, the problem should be with the last device reconnected. Follow the repair procedures for that device, then go to Verify a repair.
  3. If no errors occur, the problem could be intermittent. Make a record of the problem. Running the diagnostics for each device on the bus may provide additional information.
• Step 0050-15
  This step determines whether the SCSI Enclosure Services (SES) controller, which provides hot-plug capability for SCSI drives in the server, is causing the problem.

  Note: In most cases the SES controller is integrated on the backplane that is used to connect SCSI devices, for example a disk drive backplane. If your system has hot-plug capability and the SES controller is separate from the SCSI drive backplane, there will be an intermediate card on the SCSI bus between the SCSI adapter and the device or SCSI backplane. You will have to make a visual check to see if there are any intermediate cards on the SCSI bus that is displaying a problem.
  Does a separate SES controller plug into the SCSI device backplane?

  NO

  Go to Step 0050-18.

  YES

  Go to Step 0050-16.

• Step 0050-16
  Follow these steps:

  1. Power off the system.
  2. Remove the intermediate SES controller card. Locate the SES controller part number under System parts.
  3. Power on the system.
  4. If the Missing Options menu displays, select the option The resource has been turned off, but should remain in the system configuration for all the devices that were disconnected.
  5. Run the diagnostics in system verification mode on the adapter.
  Did a failure occur?

  NO

  Go to Step 0050-17.

  YES

  Go to Step 0050-18.

• Step 0050-17

  Follow these steps:

  1. Power off the system.
  2. Replace the intermediate SES controller card.
  3. Go to Verify a repair.
• Step 0050-18

  Follow these steps:

  1. Go to Preparing for hot-plug SCSI device or cable deconfiguration.
  2. Disconnect all cables attached to the SCSI adapter. For SCSI differential adapters in a high-availability configuration, see Considerations.
  3. Go to After hot-plug SCSI device or cable deconfiguration.
  4. If the Missing Options menu displays, select the option The resource has been turned off, but should remain in the system configuration for all the devices that were disconnected.
  5. Run the diagnostics in system verification mode on the adapter.
  Did a failure occur?

  NO

  Go to Step 0050-19.

  YES

  Replace the adapter, then go to Verify a repair.

• Step 0050-19

  Follow these steps:

  1. Go to Preparing for hot-plug SCSI device or cable deconfiguration.
  2. Reconnect the cables to the adapter.
  Does the SES controller (an intermediated SES controller) plug into the backplane?

  NO

  Go to Step 0050-20.

  YES

  Go to Step 0050-21.

• Step 0050-20

  Follow these steps:

  1. Replace the SES controller. Locate the intermediate SES controller part number under System parts.
  2. Power on the system.
  3. If the Missing Options menu displays, select the option The resource has been turned off, but should remain in the system configuration for all the devices that were disconnected.
  4. Run the diagnostics in system verification mode on the adapter.
  Did a failure occur?

  NO

  Go to Verify a repair.

  YES

  Go to Step 0050-21.

• Step 0050-21

  One of the cables remaining in the system is defective. Refer to System parts for the cable part numbers. Replace the parts one at a time in the order listed. Follow these steps for each FRU replaced:

  1. Rerun the diagnostics for the adapter.
  2. If there is any failure, continue with the next FRU.
  3. If there is no failure, go to Verify a repair.
• Step 0050-22

  Follow these steps:

  1. Go to Preparing for hot-plug SCSI device or cable deconfiguration.
  2. Disconnect all cables attached to the adapter (except for the cable to the device from which you boot to run diagnostics; you may want to temporarily move this device to another SCSI port while you are trying to find the problem).
  3. Go to After hot-plug SCSI device or cable deconfiguration.
  4. If the Missing Options menu displays, select the option The resource has been turned off, but should remain in the system configuration for all the devices that were disconnected.
  5. Run the diagnostics on the adapter.
  Did a failure occur?

  NO

  Go to Step 0050-23.

  YES

  Replace the adapter, then go to Verify a repair.

• Step 0050-23

  One of the cables remaining in the system is defective. Refer to System parts for the cable part numbers. Replace the parts one at time in the order listed. Follow these steps for each FRU replaced:

  1. Rerun the diagnostics for the adapter.
  2. If there is any failure, continue with the next FRU.
  3. If there is no failure, go to Verify a repair.