How do I troubleshoot IT infrastructure hypervisor issues?

Troubleshooting hypervisor issues in your IT infrastructure requires a systematic approach to ensure minimal downtime and efficient resolution. Below is a step-by-step guide tailored for your role:

1. Identify the Problem

Start by gathering detailed information about the issue:
- Is it a performance issue, a VM that won’t start, network connectivity problems, storage latency, or something else?
- Which hypervisor is affected (VMware ESXi, Hyper-V, KVM, etc.)?
- Note any error messages or logs that can provide clues.

2. Check the Basics

Host Status: Ensure the hypervisor host is powered on and accessible.
Hardware Health: Verify that the server hardware is functioning correctly (e.g., check server logs, RAID controller status, memory, and CPU).
Network Connectivity: Ensure the host has proper network connectivity and IP addressing.
Storage Connectivity: Confirm storage devices (SAN, NAS, or local disks) are reachable and have no hardware failures.

3. Review Hypervisor Logs

Access hypervisor logs to identify errors or warnings:
- VMware ESXi: /var/log/ directory (e.g., vmkernel.log, vpxa.log).
- Microsoft Hyper-V: Event Viewer (System and Application logs).
- KVM: /var/log/libvirt/ or journal logs.
Look for patterns or recurring issues.

4. Check Resource Utilization

Examine CPU, memory, disk I/O, and network usage on the hypervisor:
- Overcommitted resources can lead to degraded performance or VM crashes.
Use monitoring tools like VMware vSphere Performance Charts, Hyper-V Performance Monitor, or Prometheus/Grafana for KVM.

5. Verify Virtual Machine (VM) Configuration

Ensure VM settings are correct (e.g., allocated resources, compatibility with the hypervisor version).
Check if snapshots are consuming excessive disk space.
Confirm the virtual hardware is compatible (e.g., virtual NIC, disk controllers).

6. Validate Network Settings

Check virtual switch configurations:
- Are VLANs correctly configured?
- Are port groups and uplinks working properly?
Verify DNS and routing settings on the hypervisor and virtual machines.

7. Storage Troubleshooting

Check if datastore or storage is running out of space.
Verify that storage paths are redundant and operational (e.g., iSCSI, NFS, or FC connections).
Look for disk latency or high IOPS that could indicate bottlenecks.

8. Patch and Update

Ensure the hypervisor is running the latest stable version and has all necessary patches applied.
Check compatibility between hypervisor and guest OS versions.
Update firmware for host hardware components like RAID controllers and NICs.

9. Test and Isolate

Create a test VM to verify the host’s functionality.
Migrate VMs to another host (if possible) to isolate the problem.
If the issue occurs during VM migration, check vMotion settings (VMware) or Live Migration settings (Hyper-V).

10. Restart Services

Restart key hypervisor services, such as vCenter Agent (vpxa) in VMware or Virtual Machine Management Service in Hyper-V.
Reboot the hypervisor host if necessary, but only as a last resort and during a maintenance window.

11. Enable High Availability (HA) and Fault Tolerance

If HA is configured, ensure it is functioning properly to handle host failures.
Verify Fault Tolerance settings if enabled.

12. Engage Vendor Support

If troubleshooting does not resolve the issue, contact the hypervisor vendor (e.g., VMware, Microsoft, Red Hat) for assistance.
Provide logs, host details, and a description of the problem.

13. Document and Prevent

Document the issue and resolution steps for future reference.
Implement monitoring and alerting tools (e.g., VMware vRealize Operations, Nagios, Zabbix) to proactively identify problems.

Tools to Use:

VMware: ESXi CLI commands, vSphere Client, vCenter.
Hyper-V: PowerShell, Event Viewer, System Center Virtual Machine Manager (SCVMM).
KVM: virsh, Cockpit, Prometheus/Grafana.
Network: Wireshark, iperf, netstat.
Storage: SAN/NAS management tools, I/O benchmarking tools like fio.

By following these steps, you can systematically troubleshoot hypervisor issues and restore service promptly.