Book Image

KVM Virtualization Cookbook

By : Konstantin Ivanov
Book Image

KVM Virtualization Cookbook

By: Konstantin Ivanov

Overview of this book

Virtualization technologies such as KVM allow for better control over the available server resources, by deploying multiple virtual instances on the same physical host, or clusters of compute resources. With KVM it is possible to run various workloads in isolation with the hypervisor layer providing better tenant isolation and higher degree of security. This book will provide a deep dive into deploying KVM virtual machines using qemu and libvirt and will demonstrate practical examples on how to run, scale, monitor, migrate and backup such instances. You will also discover real production ready recipes on deploying KVM instances with OpenStack and how to programatically manage the life cycle of KVM virtual machines using Python. You will learn numerous tips and techniques which will help you deploy & plan the KVM infrastructure. Next, you will be introduced to the working of libvirt libraries and the iPython development environment. Finally, you will be able to tune your Linux kernel for high throughput and better performance. By the end of this book, you will gain all the knowledge needed to be an expert in working with the KVM virtualization infrastructure.
Table of Contents (15 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Reverting snapshots


In this recipe, we are going to create an internal snapshot of a running instance, introduce a change, then restore back to the original instance state using the snapshot.

Getting ready

For this recipe, we are going to need the following:

  • A libvirt host with an existing QCOW2 image
  • A running KVM instance, using the QCOW2 image
  • The QEMU toolset

How to do it...

To revert the state of a KVM instance to an older state, from an existing snapshot, run the following:

  1. Connect to the KVM instance and create a new file:
root@kvm:~# virsh console kvm1
Connected to domain kvm1
Escape character is ^]

root@debian:~# touch SNAPSHOT
root@debian:~#
root@kvm:~#
  1. Create an internal snapshot of the virtual machine:
root@kvm:~# virsh snapshot-create kvm1
Domain snapshot 1492802417 created
root@kvm:~#
  1. Get information about the snapshot:
root@kvm:~# virsh snapshot-info kvm1 --snapshotname 1492802417
Name: 1492802417
Domain: kvm1
Current: yes
State: running
Location: internal
Parent: 1492797458
Children...