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Light path diagnostics

Light path diagnostics is a system of LEDs on various external and internal components of the server that leads you to the failed component.

When an error occurs, LEDs are lit throughout the server. By viewing the LEDs in a particular order, you can often identify the source of the error.

When LEDs are lit to indicate an error, they remain lit when the server is turned off, provided that the server is still connected to power and the power supply is operating correctly and the top cover is closed and latched correctly.

Before you work inside the server to view light path diagnostics LEDs, read the safety information that begins in Safety and Handling static-sensitive devices.

If an error occurs, view the light path diagnostics LEDs in the following order:

  1. Look at the operator information panel on the front of the server.
    • If the Log LED is lit, it indicates that information about a suboptimal condition in the server is available in the IMM system-event log or in the system-event log.
    • If the system-error LED is lit, it indicates that an error has occurred; go to step 2.
      Note
      The initial server configuration will not include the light path diagnostics panel. Step 2 is for users who have upgraded the operator information panel to the advanced operator information panel. If the server only has the operator information panel, please go to step 3.

    The following illustration shows the operator information panel on the front of the server.



  2. To view the advanced operator information panel, press the blue latch on the right of the operator panel. Lit LEDs on this panel indicate the type of error that has occurred.

    Note any LEDs that are lit, and then reinstall the light path diagnostics panel in the server.

    Look at the system service label inside the server top cover, which gives an overview of internal components that correspond to the LEDs on the light path diagnostics panel. This information and the information in Light path diagnostics LEDs can often provide enough information to diagnose the error.

  3. Remove the server top cover and look inside the server for lit LEDs. Certain components inside the server have LEDs that are lit to indicate the location of a problem.

    The following illustration shows the LEDs on the system board.



LED nameDescription
Error LEDsWhen an error LED is lit, it indicates that the associated component has failed.
RTMM heartbeat LEDPower-on and power-off sequencing.
IMM 2 heartbeat LEDIndicates the status of the boot process of the IMM2.

When the server is connected to power this LED flashes quickly to indicate that the IMM2 code is loading. When the loading is complete, the LED stops flashing briefly and then flashes slowly to indicate that the IMM2 if fully operational and you can press the power-control button to start the server.

Standby power LEDWhen this LED is flashing, it indicates that the server is connected to an ac power source.

When this LED is lit, it indicates that the server is dc power on.

System board error LEDSystem-board has failed.
Microprocessor mismatch LEDWhen this LED is lit, it indicates that microprocessor 1 is not installed, or the microprocessors do not have the same cache size and type, and clock speed.
DIMM error LEDsA memory DIMM has failed or is incorrectly installed.
Microprocessor error LEDMicroprocessor has failed, is missing, or has been incorrectly installed.
Light path LEDIndicates whether or not the lightpath button is functional. If the light path LED is lit after pressing the lightpath button, it indicates that the lightpath button is functioning properly. By contrast, if the lightpath LED is not lit when pressing the light path button, it means the lightpath button is not functioning properly.