When the hostd service on an ESXi host crashes, it can impact the management and functionality of the host. Troubleshooting the issue is crucial to identify the root cause and restore normal operations. ESXi hosts maintain various logs that can provide valuable information about the cause of the crash. Below are some steps and examples to troubleshoot a hostd crash:

1. Check ESXi Logs:

ESXi hosts keep several logs that are useful for diagnosing issues. The primary logs related to hostd are located in the /var/log directory. The main logs to check are:

• /var/log/vmkernel.log: Contains ESXi kernel messages, including errors and warnings related to hostd.
• /var/log/hostd.log: Records events related to the management service (hostd), including errors, warnings, and information about host management tasks.

Example 1: Checking vmkernel.log for hostd Related Errors:

Use the following command to view the last 100 lines of the vmkernel.log:

tail -n 100 /var/log/vmkernel.log

Look for any error messages or warnings related to hostd. These may provide clues about the cause of the crash.

Example 2: Checking hostd.log for Errors and Warnings:

Use the following command to view the last 100 lines of the hostd.log:

tail -n 100 /var/log/hostd.log

Look for any errors or warnings that occurred around the time of the crash. Pay attention to messages related to communication with vCenter Server, VM management, and inventory operations.

2. Collect Core Dumps:

When hostd crashes, it may generate a core dump file that contains valuable information about the state of the process at the time of the crash. Core dumps are stored in the /var/core directory on the ESXi host.

Example 3: Collecting Core Dump Files:

Use the following command to list core dump files:

ls -al /var/core

If there are any core dump files related to hostd, you can analyze them with VMware support or debugging tools.

3. Review Hardware and System Health:

Hardware issues can sometimes lead to service crashes. Check the hardware health status of the host, including CPU, memory, storage, and networking components.

Example 4: Checking Hardware Health:

Use the following command to view hardware health information:

esxcli hardware ipmi sel list

This command displays the System Event Log (SEL) entries related to hardware events.

Example 5: Checking System Health:

Use the following command to view system health information:

esxcli hardware platform get

This command provides general hardware information about the host.

4. Identify Recent Changes:

Determine if any recent changes were made to the host’s configuration or software. Changes like updates, driver installations, or configuration adjustments may be related to the hostd crash.

Example 6: Reviewing Recent Changes:

• Check the installation and update history using the vSphere Client or PowerCLI to see if any recent updates were applied to the host.

5. Check for Resource Constraints:

Resource constraints, such as low memory or CPU availability, can lead to service crashes.

Example 7: Checking Resource Usage:

Use the following command to view CPU and memory usage:

esxtop

Press c to sort by CPU usage and m to sort by memory usage. Look for high utilization or contention.

6. Check for Network Issues:

Network problems can cause communication issues between the host and vCenter Server.

Example 8: Checking Network Configuration:

Use the following command to display the network configuration:

esxcfg-nics -l

Ensure that all network interfaces are up and properly configured.

7. Review VMware Compatibility Matrix:

Ensure that the ESXi version and hardware are compatible with each other and with vCenter Server.

Conclusion:

Troubleshooting a hostd crash involves a systematic approach, including reviewing logs, collecting core dumps, checking hardware health, identifying recent changes, checking for resource constraints, and reviewing network configuration. In many cases, analyzing the logs and core dumps will provide valuable information about the cause of the crash, allowing you to take appropriate corrective actions. If needed, involve VMware support for in-depth analysis and resolution.