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
About the Author
About the Reviewer
Customer Feedback

Attaching block devices to virtual machines

In this recipe, we are going to examine a few different ways of adding new block devices to a KVM instance. The new block device can then be partitioned, formatted, and used as a regular block device inside the guest OS. We can add disks to live running instances, or we can attach them persistently by creating XML definitions for the individual block devices offline. From the host OS, we can present any type of block device file to the guest, including iSCSI targets, LVM logical volumes, or image files.

Getting ready

For this recipe, we will need:

  • A running KVM instance with console access
  • The dd utility

How to do it...

To attach a new block device to a KVM guest, run the following:

  1. Create a new 1 GB image file:
root@kvm:~# dd if=/dev/zero of=/tmp/new_disk.img bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 0.670831 s, 1.6 GB/s

  1. Attach the file as a new disk to the KVM instance:
root@kvm:~# virsh attach...