# Basic Troubleshooting

This chapter provides guidance for diagnosing and resolving common server problems. When an issue occurs, approaching it methodically can help you find the root cause quickly.

{% hint style="success" %}
**Best Practice: Check the BMC Event Log First**&#x20;

Your first step should always be to log in to the BMC web interface and check the **System Event Log (SEL)**. The BMC logs all hardware events and will often tell you exactly what is wrong.
{% endhint %}

## **Common problems and solutions**

### **System won't power on**

If the server shows no signs of life, follow these steps:

1. **Check the source:** Ensure the rack's PDU is switched on and functioning.
2. **Check the cables:** Confirm both power cords are firmly plugged into the server's PSUs and the PDUs.
3. **Check the PSU LEDs:** Look at the small LED indicators on the power supply units themselves. A green light indicates the PSU is receiving power. If there is no light or an amber light, the PSU may be faulty or not receiving power.

### **No video output / No POST**

"No POST" means the server is not completing its Power-On Self-Test.

1. **Check the remote console first:** Always use the BMC's remote KVM to check for video output. This tells you if the problem is with the server itself or just the local monitor connection.
2. **Listen for beep codes:** If the system speaker is connected, the server may emit a pattern of beeps that indicate the specific problem (e.g., a memory or CPU issue).
3. **Reseat key components:** Power off and disconnect the server. Open the chassis and carefully reseat the memory modules and any expansion cards. An improperly seated component is a very common cause of POST failures.

### **Memory errors**

If the system boots but reports memory errors, or fails to boot with a memory error code:

1. **Check the population rules:** Ensure the DIMMs are installed in the correct slots according to the guidelines in Chapter 5.
2. **Isolate the faulty module:** If you have multiple DIMMs, try booting with a minimal configuration (one DIMM per CPU). Add modules back one by one until the error reappears to identify the faulty DIMM.
3. **Check the system event log (SEL):** The BMC logs all hardware errors, including which specific DIMM slot is reporting a problem.

### **Fans spin at full speed**

If the system fans run at 100% speed continuously and do not slow down after boot:

1. **Check for thermal events:** Use the BMC interface to check for any high-temperature warnings. Ensure the ambient room temperature is within the specified limits.
2. **Verify airflow:** Make sure the chassis top cover is correctly installed and secured. Check that no cables are blocking the fans or airflow paths inside the chassis.
3. **Check for failed sensors:** A failed temperature sensor can cause the BMC to ramp up the fans as a precaution. Check the BMC event log for any sensor-related errors.

### **BMC/IPMI is not responding**

If you cannot reach the BMC's web interface or get a response from `ping`:

1. **Check the physical connection:** Ensure the network cable is securely plugged into the dedicated **MGMT** port and the network switch. Check the link lights on the port.
2. **Check for IP conflicts:** Make sure no other device on the network is using the same IP address as the BMC.
3. **Perform a cold reboot:** As a last resort, shut down the server and disconnect the power cords for 30 seconds. This will force the BMC to completely restart.

### **Drive not detected in OS**

If a drive is not visible in the operating system or during installation:

1. **Check the physical seating:** Ensure the drive carrier is fully inserted and locked into the drive bay.
2. **Check the drive LED:** A green LED on the carrier indicates the drive has power. If there is no light, the drive may not be seated correctly.
3. **Check the BIOS:** Reboot the server and enter the BIOS setup. Check the storage or NVMe configuration pages to see if the drive is detected at the hardware level.
4. **Check the drivers:** For RAID/VROC configurations, ensure the correct storage controller driver is loaded during the OS installation.

## **Interpreting status LEDs**

The LEDs on the server provide a quick visual diagnosis of its status. This section details the function of each major LED.

{% hint style="info" %}
**Note:** LED layout and behavior may vary by model.
{% endhint %}

<figure><img src="/files/u7sFmQIbFUt5Ms4fXQoK" alt=""><figcaption></figcaption></figure>

### **Front Panel LEDs**

<table data-header-hidden><thead><tr><th width="192.41015625"></th><th width="151.3515625"></th><th></th></tr></thead><tbody><tr><td><strong>LED</strong></td><td><strong>COLOR/STATE</strong></td><td><strong>DESCRIPTION</strong></td></tr><tr><td>Power LED</td><td>Green (Solid)</td><td>System is powered on (ACPI S0).</td></tr><tr><td><br></td><td>Blinking</td><td>System is in sleep mode.</td></tr><tr><td><br></td><td>Off</td><td>System is off (ACPI S4/S5).</td></tr><tr><td>UID LED</td><td>Blue</td><td>System identified via command or button.</td></tr><tr><td>System Status LED</td><td>Green</td><td>BMC is initializing.</td></tr><tr><td><br></td><td>Red</td><td>BMC anomaly or system failure detected.</td></tr><tr><td><br></td><td>Off</td><td>System is running normally.</td></tr><tr><td>Alarm LED</td><td>Red</td><td>System failure.</td></tr><tr><td><br></td><td>Green</td><td>BMC initializing.</td></tr><tr><td><br></td><td>Off</td><td>Normal operation.</td></tr><tr><td>M.2 Activity LED</td><td>Amber</td><td>M.2 drive is present, no activity.</td></tr><tr><td><br></td><td>Blinking</td><td>M.2 drive is being accessed.</td></tr><tr><td>NIC Link LED</td><td>Green / Orange</td><td>Link established (speed dependent).</td></tr><tr><td>NIC Activity LED</td><td>Blinking</td><td>Network traffic is detected.</td></tr></tbody></table>

### **Drive Bay LEDs**

<table data-header-hidden><thead><tr><th width="160.08984375"></th><th width="151.76171875"></th><th></th></tr></thead><tbody><tr><td><strong>LED Name</strong></td><td><strong>Color</strong></td><td><strong>Description</strong></td></tr><tr><td>Activity</td><td>Green</td><td>Blinking: Read/write in progress.</td></tr><tr><td>Status</td><td>Amber/Red</td><td>Drive fault or predictive failure.</td></tr><tr><td>Power</td><td>Solid Green</td><td>Drive is powered on.</td></tr></tbody></table>

### **Network Port (RJ-45) LEDs**

Each RJ-45 LAN port includes integrated LEDs to show link and activity status

<table data-header-hidden><thead><tr><th width="149.16015625"></th><th width="152.39453125"></th><th></th></tr></thead><tbody><tr><td><strong>LED Name</strong></td><td><strong>Color</strong></td><td><strong>Description</strong></td></tr><tr><td>Link/Speed</td><td>Green</td><td>1 Gbps connection established.</td></tr><tr><td><br></td><td>Amber</td><td>100 Mbps connection.</td></tr><tr><td><br></td><td>Off</td><td>No link detected.</td></tr><tr><td>Activity</td><td>Blinking</td><td>Network traffic detected.</td></tr></tbody></table>

### **IPMI/BMC LED**

Some systems include a dedicated LED for the BMC, which may be visible on the front panel or internally on the motherboard.

<table data-header-hidden><thead><tr><th width="237.80078125"></th><th></th></tr></thead><tbody><tr><td><strong>LED Behavior</strong></td><td><strong>Description</strong></td></tr><tr><td>Blinking (1Hz)</td><td>BMC running normally.</td></tr><tr><td>Fast blinking</td><td>BMC initializing or updating.</td></tr><tr><td>Off</td><td>BMC not powered.</td></tr></tbody></table>

{% hint style="info" %}
**Notes on LED Indicators**

* LED behavior may vary slightly depending on firmware version or vendor-specific customization.
* Refer to the system’s BMC Web UI or IPMI viewer for additional sensor and event details.
* Some systems support custom LED behavior mapping via BIOS or BMC configuration.
  {% endhint %}

## **Understanding BIOS POST codes**

If the server hangs during boot, the last POST code displayed can tell you at what stage the failure occurred.

<table data-header-hidden><thead><tr><th width="113.57421875"></th><th width="195.3984375"></th><th></th></tr></thead><tbody><tr><td><strong>POST Code</strong></td><td><strong>Stage</strong></td><td><strong>Description / Common Causes</strong></td></tr><tr><td><strong>19</strong></td><td>Memory Initialization</td><td>Detecting and initializing DRAM. Check DIMM seating, population rules.</td></tr><tr><td><strong>4F</strong></td><td>DXE Phase</td><td>DXE IPL started (BIOS driver loading). Normal if system proceeds past it.</td></tr><tr><td><strong>6F</strong></td><td>DXE Initialization</td><td>BMC, USB, PCIe devices being initialized. May hang if faulty PCIe card installed.</td></tr><tr><td><strong>A2</strong></td><td>IDE/SATA Detection</td><td>Detecting storage controllers/devices. Check cable, drive type, BIOS mode.</td></tr><tr><td><strong>B2</strong></td><td>Option ROM Init</td><td>Initializing VGA/RAID/NIC ROMs. Remove/replace problematic add-in cards.</td></tr><tr><td><strong>D7</strong></td><td>Input Device Init</td><td>Keyboard or input not detected. OK for headless systems.</td></tr><tr><td><strong>FF</strong></td><td>Fatal Error / Halt</td><td>System failed to complete POST. Reset CMOS, isolate components, check PSU.</td></tr></tbody></table>


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