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

Virtual disk images and formats and basic KVM storage operations

Disk images are standard files stored on the host's filesystem. They are large and act as virtualized hard drives for guests. You can create such files using the dd command, as shown:

# dd if=/dev/zero of=/vms/dbvm_disk2.img bs=1G count=10

Here is the translation of this command for you:

Duplicate data (dd) from the input file (if) of /dev/zero (virtually limitless supply of zeros) into the output file (of) of /vms/dbvm_disk2.img (disk image) using blocks of 1 G size (bs = block size) and repeat this (count) just once (10).

Important note:

dd is known to be a resource-hungry command. It may cause I/O problems on the host system, so it's good to first check the available free memory and I/O state of the host system, and only then run it. If the system is already loaded, lower the block size to MB and increase the count to match the size of the file you wanted (use bs=1M, count=10000 instead of...