Where can I find VM logs?

Virtual machine (VM) logs contain valuable information that can help troubleshoot issues and monitor the health of your VMs. However, locating these logs can be confusing for those new to virtualized environments. This article will guide you through finding logs for the most common virtualization platforms.

Where can I find VM logs?

Overview

  • VM logs are typically found on the virtualization host system, not within the VM itself.
  • Log locations depend on the virtualization platform (VMware, Hyper-V, VirtualBox, etc.).
  • Many logs relevant to VMs are centralized on the host for convenience.
  • Log formats vary and may require special viewers for parsing.

Careful inspection of VM logs allows you to:

  • Troubleshoot boot, performance, and functional issues
  • Audit VM changes and events
  • Identify security incidents and breaches
  • Monitor resource utilization for capacity planning
  • Comply with regulatory requirements

So knowing where to access these critical logs is essential.

VMware ESXi Host Logs

For ESXi hosts, most logs are stored in the /var/log directory using defined naming conventions. Log formats include plain text and binary. Use the following paths from an ESXi host console or SSH session:

/var/log/vmkernel.log – Kernel logs

/var/log/hostd.log – ESXi host daemon logs 

/var/log/vpxa.log – VMware vCenter agent  

/var/log/dvs.log – Distributed virtual switch logs

The esxtop utility also provides real-time performance graphs and monitoring that can help diagnose issues.

Key vSphere platform logs are available in the vSphere Web Client under Monitor > Logs, including:

  • VMware vCenter Server service logs
  • ESXi hypervisor logs
  • Individual VM logs

Third party tools like vSphere Log Insight can parse these logs for improved analysis.

Microsoft Hyper-V Host Logs

Hyper-V managers and users can locate key logs in the Windows host at:

C:\Windows\System32\winevt\Logs\ – Application, security, etc. event logs

C:\Windows\debug – Boot debugging files

C:\ProgramData\Microsoft\Windows\Hyper-V – VM configuration and status logs

PowerShell cmdlets like Get-VM also provide VM status details.

The Hyper-V Manager console supplies basic VM health monitoring but third party tools can provide deeper log analytics.

Other Platforms

Administrators can find logs in the following locations for other common virtualization platforms:

VirtualBox

  • Linux: /var/log/vbox-{platform}.log
  • Windows: C:\Users\{user}\VirtualBox VMs\{vm}\Logs\{vm}.log

KVM

  • /var/log/libvirt – Libvirt daemon logs
  • /var/log/qemu – QEMU emulator logs

Docker

  • docker logs {container} – Prints app logs for containers
  • Host daemon logs in /var/log/docker.log

Carefully inspecting platform-specific and VM-specific logs allows full visibility into virtualized environments. Now that you know the common log locations, you can better monitor and operate your critical VMs.

Key Takeaway

  • VM logs provide invaluable troubleshooting data but their location depends on your virtualization platform.
  • For VMware ESXi, logs are found in /var/log/* and the vSphere Web Client.
  • Microsoft Hyper-V logs are located in C:\Windows\System32\winevt\Logs\, C:\Windows\debug, etc.
  • Check /var/log for VirtualBox, KVM, Docker hosts, and other platforms.
  • Third-party tools can help parse and analyze VM logs for actionable insights.

Conclusion

I hope this guide has eliminated any confusion over where to access virtual machine logs on hosts like VMware vSphere, Hyper-V, VirtualBox, and KVM. These logs provide the definitive source of truth when troubleshooting performance, stability, and security issues.

Centralizing logs and giving them consistent naming conventions allows administrators to quickly narrow down problems. Make sure to use the recommended third-party tools for sorting and filtering data within verbose log files.

With these VM logging best practices, virtualization teams can achieve improved uptime, faster issue diagnosis, and more robust documentation of events. Getting familiar with all the locations highlighted here is critical for both reactive and proactive management.

FAQs

Q: Where are VMware ESXi boot logs located?
A: ESXi boot logs are found in /var/log/boot.log files on the ESXi host.

Q: What permission is needed to view Hyper-V logs?
A: Administrators must be a member of the local Hyper-V Administrators group to access Hyper-V logs.

Q: How can I export VM logs for sharing?
A: Use commands like virsh dumpxml for libvirt/KVM VMs or vSphere’s Export Diagnostic Data to share detailed VM logs.

Q: Where does VirtualBox store crash dumps for VMs?
A: VirtualBox VM crash dumps can be found in C:\Program Files\Oracle\VirtualBox\VBoxSVC.log on Windows hosts.

Q: How do I analyze VMware vSphere esxtop data?
A: esxtop provides real-time graphs and statistics on CPU/memory usage, network I/O, disk latency, etc to diagnose performance problems.

Q: Can I access Docker container logs without SSH?
A: Yes, you can use docker logs -f [container] on the Docker host itself or integrate with Docker swarm/logging drivers.

Q: What VMware vCenter log shows permissions errors?
A: Check vpxd-svcs.log under vCenter Server logs for permission issues when managing vSphere.

Q: Where are detailed libvirtd logs on CentOS 7?
A: Libvirt daemon logs are stored at /var/log/libvirt/libvirtd.log on CentOS 7 hosts.

Q: How can I tell if a Hyper-V VM crashed from event logs?
A: Event ID 12294 in Windows event logs signifies an unexpected VM crash occurred.

Q: What sections of esxtop should I check during network problems?
A: The NET stats and CMDs/s stats in esxtop provide insight into VM network bottlenecks during issues.

Q: Does Docker retain logs after a container stops?
A: No, Docker deletes a container’s stderr/stdout logs after it is stopped or removed. Persistent logging requires docker daemon config changes.

Q: Where can I change log rotation settings on ESXi?
A: Modify the /etc/vmware/hostd/config.xml file and restart hostd to alter ESXi log rotations.

Q: What Hyper-V log shows Dynamic Memory allocations?
A: Hyper-V’s Memory Manager log provides data on VM startup memory settings and Dynamic Memory reallocations.

Q: How do I troubleshoot VirtualBox VM crashes?
A: Enable crash dump saving in Global Settings, then inspect the VBoxSVC.log after crashes for call stacks.

Q: Can I remotely access ESXi host logs?
A: Yes, use the ESXi Embedded Host Client or SSH to securely connect and view host logs remotely.

Q: Where are background process logs in vSphere?
A: Service logs under vCenter’s management view show vpxd, VMware AFD, and other background processes.

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