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VMware Logs: Finding the Right Log for Your Problem(s)

phatq
Virtualization0 Comments 011 min read

In a VMware environment, encountering various problems is part of the day-to-day operations. With a multitude of log files VMware produces, it can sometimes be overwhelming to pinpoint the right log file for a specific issue. Here’s a basic and practical overview with some use cases to help you navigate through the key VMware log files, understand their purposes, and know exactly where to find them when a problem arises.

The Essentials of VMware Log Files

VMware environments generate several log files, each serving specific purposes and containing different types of information. Here’s a breakdown of the most important log files, where they are located, and how to access them.

1. VMkernel Log (vmkernel.log)

  • Purpose: Logs information related to the VMkernel, including device discovery, storage, networking issues, and general system performance.
  • Location: ESXi host – /var/log/vmkernel.log
  • Access Steps:
    1. Connect to the ESXi host via SSH or the ESXi shell.
    2. Navigate to the log directory: cd /var/log
    3. View the log file: less vmkernel.log
  • Use Case: If virtual machines are experiencing slow performance or you suspect storage latency issues, this log is your go-to for error messages related to storage devices or network latency.

2. VMware ESXi Host Agent Log (hostd.log)

  • Purpose: Contains logs for the ESXi host management service (hostd). It includes information about virtual machine power operations, host agent events, and interactions with the vCenter Server.
  • Location: ESXi host – /var/log/hostd.log
  • Access Steps:
    1. Connect to the ESXi host via SSH or the ESXi shell.
    2. Navigate to the log directory: cd /var/log
    3. View the log file: less hostd.log
  • Use Case: If virtual machines are not responding to start or stop commands, examining the hostd.log can provide insights into potential configuration issues or communication problems with vCenter.

3. Virtual Center Server Log (vpxd.log)

  • Purpose: Logs for the vCenter Server service, including information about vCenter operations, inventory changes, task execution, and user actions.
  • Location: vCenter Server – /var/log/vmware/vpxd/vpxd.log
  • Access Steps:
    1. Connect to the vCenter Server appliance via SSH.
    2. Navigate to the log directory: cd /var/log/vmware/vpxd
    3. View the log file: less vpxd.log
  • Use Case: When changes in the vCenter inventory are not reflected or tasks initiated via the vCenter UI are failing, you would check vpxd.log for errors or warnings that indicate the underlying cause.

4. Virtual Machine Log (vmware.log)

  • Purpose: Each virtual machine has its own log file that logs VM-specific events, such as power operations, configuration changes, and guest OS errors.
  • Location: ESXi host – located in the VM’s directory on the datastore, e.g., [datastore] VM_Name/vmware.log
  • Access Steps:
    1. Use the vSphere Client to browse the datastore where the VM is located.
    2. Navigate to the VM’s directory.
    3. Download and open the vmware.log file for analysis.
  • Use Case: If a specific VM is crashing or failing to start, analyze its vmware.log to understand what is happening during the VM boot process or identify errors thrown by the guest OS.

5. ESXi Shell Log (shell.log)

  • Purpose: Records all commands and operations executed in the ESXi Shell.
  • Location: ESXi host – /var/log/shell.log
  • Access Steps:
    1. Connect to the ESXi host via SSH or the ESXi shell.
    2. Navigate to the log directory: cd /var/log
    3. View the log file: less shell.log
  • Use Case: When unauthorized changes or suspicious activities are suspected on an ESXi host, review shell.log to trace the exact commands executed, assisting in security audits or troubleshooting.

6. Syslog (syslog.log)

  • Purpose: A general log that includes system-wide messages, useful for overall system monitoring.
  • Location: ESXi host – /var/log/syslog.log
  • Access Steps:
    1. Connect to the ESXi host via SSH or the ESXi shell.
    2. Navigate to the log directory: cd /var/log
    3. View the log file: less syslog.log
  • Use Case: For a broad overview of system health or when investigating events that do not fall into more specific categories, syslog can provide a comprehensive view of the system’s state and events.

Sum-up Use Cases

Scenario 1: Network Latency Issues

  • Symptom: VMs are experiencing network latency.
  • Logs to Check: vmkernel.log
  • Analysis: Look for messages related to network performance issues, such as dropped packets or high latency times, which can help identify the cause of the latency.

Scenario 2: VM Power Operations Failures

  • Symptom: VMs are not responding to start or stop commands.
  • Logs to Check: hostd.log
  • Analysis: Examine the log for errors related to VM operations. Issues might include configuration problems or communication issues between the host and vCenter.

Scenario 3: vCenter Task Failures

  • Symptom: Tasks initiated via the vCenter UI are failing.
  • Logs to Check: vpxd.log
  • Analysis: Check for errors or warnings that indicate why the task failed. This could be due to permission issues, configuration problems, or connectivity issues with the hosts.

Scenario 4: VM Crashes

  • Symptom: A specific VM is crashing or failing to start.
  • Logs to Check: vmware.log
  • Analysis: Analyze the log to understand what is happening during the VM boot process. Look for specific errors thrown by the guest OS or issues related to VM configuration.

Scenario 5: Unauthorized Changes on ESXi Host

  • Symptom: Suspicion of unauthorized changes or activities on an ESXi host.
  • Logs to Check: shell.log
  • Analysis: Review the log to trace the exact commands executed. This helps in auditing and identifying any unauthorized or suspicious activities.

Scenario 6: Issues with vSphere Client

  • Symptom: Users are experiencing issues accessing or interacting with the vSphere Client.
  • Logs to Check: vsphere-client.log
  • Analysis: Identify client-side problems or misconfigurations affecting the user experience by examining the logs for errors or warnings.

Scenario 7: General System Monitoring

  • Symptom: Broad overview of system health or investigating non-specific events.
  • Logs to Check: syslog.log
  • Analysis: Use syslog to get a comprehensive view of the system’s state and events. It helps in identifying patterns or events that do not fall into specific categories.

Summary

Understanding and effectively analyzing these logs can significantly aid in troubleshooting and maintaining the health and performance of your VMware environment. By knowing where to find the right log file and how to interpret it, you can quickly address issues and ensure smooth operations in your virtualized environment.