Book Image

Mastering KVM Virtualization - Second Edition

By : Vedran Dakic, Humble Devassy Chirammal, Prasad Mukhedkar, Anil Vettathu
Book Image

Mastering KVM Virtualization - Second Edition

By: Vedran Dakic, Humble Devassy Chirammal, Prasad Mukhedkar, Anil Vettathu

Overview of this book

Kernel-based Virtual Machine (KVM) enables you to virtualize your data center by transforming your Linux operating system into a powerful hypervisor that allows you to manage multiple operating systems with minimal fuss. With this book, you'll gain insights into configuring, troubleshooting, and fixing bugs in KVM virtualization and related software. This second edition of Mastering KVM Virtualization is updated to cover the latest developments in the core KVM components - libvirt and QEMU. Starting with the basics of Linux virtualization, you'll explore VM lifecycle management and migration techniques. You’ll then learn how to use SPICE and VNC protocols while creating VMs and discover best practices for using snapshots. As you progress, you'll integrate third-party tools with Ansible for automation and orchestration. You’ll also learn to scale out and monitor your environments, and will cover oVirt, OpenStack, Eucalyptus, AWS, and ELK stack. Throughout the book, you’ll find out more about tools such as Cloud-Init and Cloudbase-Init. Finally, you'll be taken through the performance tuning and troubleshooting guidelines for KVM-based virtual machines and a hypervisor. By the end of this book, you'll be well-versed with KVM virtualization and the tools and technologies needed to build and manage diverse virtualization environments.
Table of Contents (22 chapters)
Section 1: KVM Virtualization Basics
Section 2: libvirt and ovirt for Virtual Machine Management
Section 3: Automation, Customization, and Orchestration for KVM VMs
Section 4: Scalability, Monitoring, Performance Tuning, and Troubleshooting

Enabling debug mode logging

There's another approach to logging in KVM: configuring debug logging. In the libvirtd configuration file that we just mentioned, there are additional settings you can use to configure this very option. So, if we scroll down to the Logging controls part, these are the settings that we can work with:

  • log_level
  • log_filters
  • log_outputs

Let's explain them step by step. The first option – log_level – describes log verbosity. This option has been deprecated since libvirt version 4.4.0. In the Logging controls section of the file, there's additional documentation hardcoded into the file to make things easier. For this specific option, this is what the documentation says:

Figure 16.1 – Logging controls in libvirtd.conf

What people usually do is see the first part of this output (Logging level description), go to the last line (Iog_level), set it to 1, save, restart the libvirtd service...