Apple xserve early 2009 User Manual

							Xserve (Early 2009) General Troubleshooting — Block Diagram  21 2010-06-28
Block Diagram   
						

							Xserve (Early 2009) General Troubleshooting — Diagnostic LEDs 22 2010-06-28
Diagnostic LEDs
Logic Board Diagnostic LEDs
The Xserve (Early 2009) logic board includes a set of LEDs to help service providers 
troubleshoot the computer. The LEDs are located on the logic board below the DIMM 
connectors, at the rear of the unit, to the left side of the unit (looking from the back), and on 
the Drive Interconnect Backplane or Xserve RAID Card. 
Some tips:
• You must remove the unit from its rack and place it on a sold surface with its cover removed 
in order to view these LEDs. Most internal diagnostic LEDs are only enabled to come on when 
the cover is removed (memory DIMM LEDs remain ON even with the cover in place).
• Do not attempt to troubleshoot the unit solely by these LEDs alone. Use this information to 
guide your troubleshooting, not lead it.
If a specific error condition exists, there should be corresponding LED evidence to help verify 
and isolate the issue. However, it is not possible to deduce a fault or isolate a specific symptom 
solely by examining these LEDs out of context.  
						

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1. System State LEDs
Use the following table to interpret the LEDs.
LocationNameColorNominalIndicates
S0Power ONGreenOn; off when 
in standby 
mode
System is 
running
S3SleepGreenOff, on when 
Xserve is in 
sleep mode
System is in 
sleep mode
S5StandbyGreenOff; on when 
Xserve is in 
standby
Standby 
mode, 
illuminates 
when AC 
power is 
attached  
						

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2. CPU Error LEDs
Use the following table to interpret the LEDs.
LocationColorNominalIndicates
CPU_PWRGDGreenOff; on to indicate 
hardware power has 
passed
Power chain in hardware
RSM_RSTYellow, RedOffFault preventing CPU from 
executing instructions
SYS_PWRGDGreenOn at power-on to 
indicate power has 
passed 
Power chain in hardware
PLT_RSTRedOff; on Yellow at 
power on
Platform reset
CPU B OVERTEMPRedOff; on if CPU B core 
exceeds normal 
temperature
Temperature of CPU B core 
status
IOH OVERTEMPRedOff; on if IOH exceeds 
normal temperature
Temperature of IOH status
CPU A OVERTEMPRedOff; on if CPU A core 
exceeds normal 
temperature
Temperature of CPU A core 
status
MXM OVERTEMPRedOff; on if MXM video 
card exceeds normal 
temperature
Temperature of MXM video 
card status  
						

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Platform Reset
Normally remains on during standby. This LED flashes on (yellow) briefly at power-on. LED 
should turn off as system powers up and begins to execute instructions. 
Overtemp LEDs
Normally off. These LEDs come on if an error occurs.
If LED is solidly on, it may indicate a processor over-temperature condition. Initial processor 
over-temperature can cause symptoms such as sluggish computer performance. Chronic 
processor over-temperature can cause the computer to hang completely.
Troubleshooting: 
• Verify proper heatsink installation. 
• Verify all fans are operating properly, especially the fan array.
• If both overtemp LEDs come on immediately when the computer is turned on, a faulty 
power supply could be one cause of this behavior. Replace power supply.
• Try swapping CPU A and CPU B locations. If the CPU Error LED follows the CPU, replace that 
CPU.
3. EFI POST (Power On Self Test) LEDs
This group of eight LEDs are arranged into two sets of four LEDs, representing a binary code 
that only has any significance during the short time between power-on and the unit begins to 
boot the OS, while the CPU is executing EFI code only. At no other time should these LEDs be 
used or interpreted to mean anything meaningful.
The code is more easily described as two Hexadecimal digits ranging from $00 to $FF, to make 
it easier to list and compare during troubleshooting. Each ONE represents an LED that is ON, 
and each ZERO represents an LED that is OFF
Normal power-up LED sequence:
• The sequence of codes below is typical in the first few seconds of a functioning unit’s boot 
cycle, immediately following power-on, during the EFI phase of startup.
• If your system is not booting you should check these LEDs closely to verify the sequence of 
codes has been executed in addition to your normal troubleshooting steps. Each code will only 
remain ON GREEN for a split-second each. The entire sequence takes only a few seconds to 
progress through.
• To see this sequence, power-on the unit (use the remote power on/off button on the logic 
board) while holding down the option key on an attached USB keyboard, to invoke the EFI 
startup manager and prevent the unit from leaving EFI and booting into any OS. Do this as you 
watch these LEDs as they progress through the following sequence:
Begin (power-on)  
						

							Xserve (Early 2009) General Troubleshooting — Diagnostic LEDs 26 2010-06-28
$Bx = 1 0 1 1 X X X X = All $Bx codes below are memory init codes (x may be any code 0 - F)
$BF = 1 0 0 1 1 1 1 1 = If the unit does not progress past any $Bx memory init codes, this could 
indicate a memory issue regardless of whether DIMM diagnostic error LEDs are ON or not.
$12 = 0 0 0 1 0 0 1 0 = After memory initialization has successfully completed
$51 = 0 1 0 1 0 0 0 1 = Video driver enabled beyond this point. Attached display should be 
displaying an image now. If not, this may indicate a graphics card issue.
$F9 = 1 1 1 1 1 0 0 1 = EFI finished and passed on control to OS boot loader
4. CPU Voltage LEDs
This group of LEDs will normally FLASH RED briefly during power-on, then should normally 
remain ON solidly GREEN when all voltage regulators are functioning properly to provide 
voltages to CPU A and CPU B, as well as IOH.
If any of these LEDs remain ON RED, this indicates that the corresponding voltage regulator is 
enabled but not providing any voltage output.
In single processor units the LED group for the second processor are not present.  
						

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5 & 6. Memory Diagnostic LEDs (A1 - A6 and B1 - B6)
This group of LEDs will normally remain OFF during power-on and throughout normal 
operation. If any of these LEDs come ON RED, this indicates that the corresponding DIMM (or 
its slot) may be faulty. To verify whether the fault lies with the DIMM or the slot, power down 
the unit and move the DIMM to another slot. If the DIMM is faulty, the LED adjacent to its new 
slot should come ON RED when power is reapplied. If a known-good DIMM is installed in the 
suspect slot and the LED adjacent to this slot should come ON RED , this may indicate a faulty 
DIMM slot on the logic board.
How to Troubleshoot Memory LEDs
1. Remove and reseat DIMM
2.  Restart computer. If associated LED is no longer illuminated, issue is resolved
3. If associated LED remains illuminated, replace DIMM with new DIMM
4.  Restart computer and verify LED is no longer illuminated  
						

							Xserve (Early 2009) General Troubleshooting — Diagnostic LEDs 28 2010-06-28
7. Reset Buttons
System Management Controller (SMC) Reset
The System Management Controller (SMC) is a chip on the logic board that controls all power 
functions for the Xserve. If the Xserve is experiencing any power issue, resetting the SMC may 
resolve it. The SMC controls several functions, including:
• Telling the Xserve when to turn on, turn off, sleep, wake, idle, and so forth
• Handling system resets from various commands
• Controlling the fans
It is also recommended that the SMC be reset on any new logic board after it is installed as part 
of a repair.
Note that resetting the SMC does not reset the PRAM. Resetting the SMC will not resolve issues 
in which the Xserve is unresponsive—in these situations, restarting the Xserve will generally 
suffice.
If the Xserve isn’t responding, perform these steps one at a time, in the following order, until 
the issue has been resolved:
1. Force Quit (Option-Command-Escape)
2. Restart (Control-Command-Power)
3. Force Shut Down (press the power button for 10 seconds)
4. Remove the Xserve from the rack (if applicable)
5. Remove the Top Case
6. Press the SMC Reset button on the logic board
Resetting the SMC can resolve some Xserve issues such as not starting up, not displaying video, 
sleep issues, fan noise issues, and so forth. If the Xserve still exhibits these types of issues after 
you’ve restarted the Xserve, try resetting the SMC. There are two ways to reset the SMC on the 
Xserve.
System Management Control (SMC) Reset in Rack
1. Shut Down the Xserve, either locally or using remote commands (or if the Xserve is not 
responding, hold the power button until it turns off ).
2. Unplug the AC power cord.
3. Wait at least 15 seconds.
4. Plug the power cord back in, making sure the power button is not being pressed at the time.  
						

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5. Press the power button to start up the Xserve.
Power ON / OFF Button
Behaves exactly like the front panel power button, and can be used as an alternate way to turn 
the unit on and off if needed.
Reset Buttons
When pressed, resets CPUs regardless of what is currently running. This reset overrides all 
software processes and restarts the system. Use with caution as this form of reset may corrupt 
software or files on a drive.
Drive Interconnect Backplane LEDs
Note: The following information describes the diagnostic LEDs present on the interconnect 
backplane. 
This group of eight LEDs are arranged into two sets of four LEDs, representing information 
about the SATA / SAS communication between the drive controller channels on the drive 
interconnect backplane and the drive modules themselves. The optional SSD drive does not 
have a representative LED on this board.
There is also a ‘heartbeat’ LED on this board which starts flashing ON GREEN and OFF when EFI 
loads immediately after power-on and continues to flash ON and OFF during normal operation.
The first group of four LEDs indicates activity for the four I/O channels corresponding to the 
three drive bays. Since there are only three drive bays, the fourth I/O channel and LED are not 
used and should remain OFF during normal operation.
The second group of four LEDs indicates that the controller has recognized that a drive 
module is present and connected. These LEDs are normally solidly ON GREEN when no drive 
is present, and turn OFF when a drive module has been inserted into the corresponding drive   
						

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bay and the controller has recognized this event. The LED will turn ON GREEN again when the 
corresponding drive module has been removed from its bay. 
Since there are only three drive bays, the fourth I/O channel and LED are not used and should 
remain ON GREEN during normal operation.
When you power-on the system, you should see the following activity sequence on these LEDs:
1. The entire group of eight LEDs should come ON solid GREEN when power is applied and 
remain on for a few seconds.
2.  The heartbeat LED begins flashing when EFI loads in the first few second after power-on. 
The first group of four activity LEDs should now turn OFF. The second group of four ‘drive 
present’ LEDs should remain on for a few more seconds.
3. The second group of four ‘drive present’ LEDs should each turn OFF as the controller scans 
and recognizes each connected drive module in turn, from bay 1 to bay 3 in order. The 
fourth LED should remain ON since no drive is present on the fourth I/O channel.
4.  Beyond this point, the only LEDs that should be flashing are among the first group of four 
drive activity LEDs, to indicate drive activity between a corresponding drive module, such 
as the boot drive module booting the OS, and the drive controller.