Mastering KVM Virtualization

By Humble Devassy Chirammal, Prasad Mukhedkar and Anil Vettathu

About This Book

• Become an expert in Linux virtualization
• Migrate your virtualized datacenter to the cloud
• Find out how to build a large scale virtualization solution that will transform your organization

Who This Book Is For

Linux administrators, DevOps practitioners, and Developers - if you want to build incredible, yet manageable virtualization solutions with KVM this is the book to get you there.

• Language: English
• Publisher: Packt Publishing
• Release date: Aug 19, 2016
• ISBN: 9781784396916

Book preview

Table of Contents

Mastering KVM Virtualization

Credits

About the Authors

About the Reviewers

www.PacktPub.com

eBooks, discount offers, and more

Why subscribe?

Preface

What this book covers

What you need for this book

Who this book for

Conventions

Reader feedback

Customer support

Downloading the color images of this book

Errata

Piracy

Questions

1. Understanding Linux Virtualization

What is virtualization?

Why should I use Linux virtualization?

Types of virtualization

Advantages of virtualization

Operating system virtualization/partitioning

Full virtualization

Paravirtualization

Hardware assisted virtualization

Introducing VMM/hypervisor

Type 1 and Type 2 hypervisors

Open source virtualization projects

Xen

Introducing KVM

High-level overview of KVM

What Linux virtualization offers you in the cloud

Summary

2. KVM Internals

Getting acquainted with libvirt and its implementation

Internal workings of libvirt

Time to think more about QEMU

Qemu – KVM internals

Data structures

Threading models in QEMU

KVM in action

KVM APIs

Anonymous inodes and file structures

Data structures

Execution flow of vCPU

Summary

3. Setting Up Standalone KVM Virtualization

Getting acquainted with libvirt

Host system requirements

Determining the right system requirements for your environment

Physical CPU

CPU cores

Physical memory

Storage

How much SWAP space is recommended?

Network

Setting up the environment

Installing virtualization packages

Starting the libvirt service

Validate and understand your system's virt capabilities

Hardware configuration examples

Summary

4. Getting Started with libvirt and Creating Your First Virtual Machines

Introducing virt-manager

The Virtual Networks tab

NATed virtual network

Routed virtual network

Isolated virtual network

Default network

Storage tab

Creating virtual machines using the Virtual Machine Manager

Creating a new virtual machine wizard

The Network installation (HTTP, FTP, or NFS) method

Network Boot (PXE)

Importing an existing disk image

Introducing virt-install

Installing a Windows 7 Guest using the virt-install command

Automated virtual machine deployment

Introducing virt-builder

Introducing oz

The oz configuration file

Creating a virtual machine using oz

Summary

5. Network and Storage

Virtual networking

Virtual networking using libvirt

Isolated virtual network

Routed virtual network

Editing a virtual network

NATed virtual network

MacVTap

PCI passthrough

It's all about storage!

Working with unmanaged storage

Creating a disk image and attaching it to a guest

Getting image information

Attach a disk using virt-manager

Attach a disk using virsh

Working with managed storage

Storage management console

Creating storage pools

File system directory backed storage pool

LVM Volume Group backed storage pool

iSCSI backed storage pool

Creating an ISO image library

Deleting a storage pool

Deleting storage pool using virt-manager

Deleting storage pool using virsh

Creating storage volumes

Creating volume using virsh command

Deleting a volume using the virsh command

Summary

6. Virtual Machine Lifecycle Management

QEMU guest agent

Virtual video cards and graphics

Virtual video card

Graphics

VNC graphics server

SPICE graphics server

Adding SPICE graphics server

Methods to access a virtual machine console

VM migration

Offline migration

Live or online migration

Benefits of VM migration

Setting up the environment

Shared storage

Offline migration

What if I start the VM accidently on both the hypervisors?

Enabling lockd

Live or online migration

Future of migration

Summary

7. Templates and Snapshots

Introducing virtual machine templates

Working with templates

Creating templates

Example 1 – preparing a CentOS 7 template with a complete LAMP stack

What is virt-sysprep?

Example 2 – preparing a Windows 7 template with a MySQL database

Deploying virtual machines from a template

Deploying VMs using the clone provisioning method

Deploying VMs using the thin provisioning method

Snapshots

VM disk image formats

Converting a VM disk format

Working with internal snapshots

Creating the first internal snapshot

Creating an internal snapshot with a custom name and description

Creating multiple snapshots

Reverting to internal snapshots

Deleting internal snapshots

Managing snapshots using virt-manager

Working with external disk snapshots

Creating an external disk snapshot

What is quiesce?

Reverting to external snapshots

Deleting external disk snapshots

Best practices for dealing with snapshots

Summary

8. Kimchi – An HTML5-Based Management Tool for KVM/libvirt

Libvirt Web API

Introduction to the Kimchi project

Kimchi architecture

Setting up Kimchi server

Starting kimchid service

Managing KVM virtualization infrastructure using kimchi WebUI

Creating virtual machines through Kimchi WebUI

Editing a virtual machine's resource allocation

Accessing a virtual machine's graphical console

Permissions and user access control

Monitoring and managing a host system with the Kimchi WebUI

Host system management using the Kimchi-Ginger plugin

Managing virtual machine through android phones

Summary

9. Software-Defined Networking for KVM Virtualization

Introducing Software Defined Networking

Limitations of Linux bridges

Introducing Open vSwitch

Comparison between Linux bridge and Open vSwitch

Open vSwitch architecture

Open vSwitch installation and setup

Starting openvswitch.service

Open vSwitch kernel module

Getting started with the Open vSwitch command-line interface

Setting up your first Open vSwitch bridge

Configuring an Open vSwitch bridge manually using the ovs-vsctl command

Configuring an Open vSwitch bridge using network scripts

Integrating KVM VMs and OVS

VLANs with Open vSwitch

Configuring VLANs for KVM virtual machines

Using libvirt integration

Open vSwitch QoS – controlling KVM VM traffic

Applying traffic rate limiting

Controlling outbound (egress) traffic

Applying traffic shaping

Overlay networks

Configuring Open vSwitch tunnels with VxLan

KvmHOST1 host side configuration

kvmHOST2 host configuration

Network port mirroring

Configuring port mirroring

Managing Open vSwitch using the OpenDaylight SDN controller

Installing the OpenDaylight controller (ODL-sys)

Hardware requirements

Installing and configuring ODL

Adding an Open vSwitch (vswitch001) instance to the OpenDaylight controller on system (ODL-sys)

Installing flows on the OVS bridge using OpenDaylight Dashboard

Basic Open vSwitch troubleshooting

Summary

10. Installing and Configuring the Virtual Datacenter Using oVirt

Introducing oVirt

oVirt architecture

The oVirt engine

The oVirt node

Storage

Networking

Installing the oVirt engine

Preparing the system for oVirt engine installation

Installing oVirt node

Summary

11. Starting Your First Virtual Machine in oVirt

Getting acquainted with oVirt data center and cluster

Initiating an oVirt data center

Creating storage domains

Creating logical networks

Creating and starting a virtual machine

What next?

Summary

12. Deploying OpenStack Private Cloud backed by KVM Virtualization

OpenStack architecture

Core OpenStack components

OpenStack deployment

RDO OpenStack

RDO OpenStack deployments methods

Installing Packstack

Prerequisites

Installing the Packstack installer

Running Packstack to install OpenStack

Launching First Instance

Troubleshooting the virtualization layer of OpenStack

Accessing the instance configuration database

QEMU Monitor Protocol

Summary

13. Performance Tuning and Best Practices in KVM

VirtIO

CPU tuning

The number of vCPUs

CPU configuration

CPU topology

CPU pinning

The numactl command

Working with memory

Memory allocation

Memory tuning

Memory backing

locked

nosharepages

hugepages

Getting acquainted with Kernel Same Page merging

KSM packages and files

Tuning CPU and memory with NUMA

What is NUMA?

NUMA memory allocation policies

numatune

emulatorpin

KSM and NUMA

Automatic NUMA balancing

Understanding numad and numastat

Disk and block I/O tuning

Cache mode

I/O mode

I/O tuning

Networking tuning in KVM

How to turn it on?

KVM guest time-keeping best practices

kvm-clock

Summary

14. V2V and P2V Migration Tools

Introducing the virt-v2v utility

How does virt-v2v work?

Getting the virt-v2v utility

Preparing for the v2v conversion

Conversion process

VMware guest conversion

Converting a VMware vSphere guest to a standalone KVM host

Converting a VMware vSphere guest to oVirt

Converting a VMware vSphere guest to an OpenStack-Glance repository

Xen guest conversion

Converting standalone KVM guests to an oVirt Virtualization platform and the OpenStack cloud

Troubleshooting virt-v2v related issues

Physical system to virtual conversion

Creating a virt-p2v bootable image

Can we convert any physical computers to virtual using virt-v2v?

Booting a physical system using a virt-p2v bootable disk for conversion

Converting virtual machines from unsupported virtualization platforms

List of input and output methods supported with virt-v2v

Summary

A. Converting a Virtual Machine into a Hypervisor

Introducing nested KVM

How to enable nested KVM?

Index

Mastering KVM Virtualization

---

Mastering KVM Virtualization

Copyright © 2016 Packt Publishing

All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.

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First published: August 2016

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Credits

Authors

Humble Devassy Chirammal

Prasad Mukhedkar

Anil Vettathu

Reviewers

Aric Pedersen

Ranjith Rajaram

Amit Shah

Commissioning Editor

Kunal Parikh

Acquisition Editor

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Technical Editor

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Graphics

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Cover Work

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About the Authors

Humble Devassy Chirammal works as a senior software engineer at Red Hat in the Storage Engineering team. He has more than 10 years of IT experience and his area of expertise is in knowing the full stack of an ecosystem and architecting the solutions based on the demand. These days, he primarily concentrates on GlusterFS and emerging technologies, such as IaaS, PaaS solutions in Cloud, and Containers. He has worked on intrusion detection systems, clusters, and virtualization. He is an Open Source advocate. He actively organizes meetups on Virtualization, CentOS, Openshift, and GlusterFS. His Twitter handle is @hchiramm and his website is http://www.humblec.com/.

I would like to dedicate this book in the loving memory of my parents, C.O.Devassy and Elsy Devassy, whose steady, balanced, and loving upbringing has given me the strength and determination to be the person I am today. I would like to thank my wife, Anitha, for standing beside me throughout my career and for the effort she put in taking care of our son Heaven while I was writing this book. Also, I would like to thank my brothers Sible and Fr. Able Chirammal, without whose constant support this book would not have been possible.

Finally, a special thanks to Ulrich Obergfell for being an inspiration, which helped me enrich my knowledge in virtualization.

Prasad Mukhedkar is a senior technical support engineer at Red Hat. His area of expertise is designing, building, and supporting IT infrastructure for workloads, especially large virtualization environments and cloud IaaS using open source technologies. He is skilled in KVM virtualization with continuous working experience from its very early stages, possesses extensive hands-on and technical knowledge of Red Hat Enterprise Virtualization. These days, he concentrates primarily on OpenStack and Cloudforms platforms. His other area of interest includes Linux performance tuning, designing highly scalable open source identity management solutions, and enterprise IT security. He is a huge fan of the Linux GNU Screen utility.

Anil Vettathu started his association with Linux in college and began his career as a Linux System Administrator soon after. He is a generalist and is interested in Open Source technologies. He has hands on experience in designing and implementing large scale virtualization environments using open source technologies and has extensive knowledge in libvirt and KVM. These days he primarily works on Red Hat Enterprise Virtualization, containers and real time performance tuning. Currently, he is working as a Technical Account Manager for Red Hat. His website is http://anilv.in.

I'd like to thank my beloved wife, Chandni, for her unconditional support. She took the pain of looking after our two naughtiest kids, while I enjoyed writing this book. I'd like also like to thank my parents, Dr Annieamma & Dr George Vettathu, for their guidance and to push me hard to study something new in life. Finally, I would like to thank my sister Dr. Wilma for her guidance and my brother Vimal.

About the Reviewers

Aric Pedersen is the author of cPanel User Guide and Tutorial and Web Host Manager Administration Guide, both written for Packt Publishing. He has also served as a reviewer for CUPS Administrative Guide, Linux E-mail, and Linux Shell Scripting Cookbook, published by Packt Publishing.

He has over 11 years of experience working as a systems administrator. He currently works for http://www.hostdime.com/, the world-class web host and global data center provider, and also for https://netenberg.com/, the makers of Fantastico, the world's most popular web script installer for cPanel servers.

I would like to thank Dennis and Nicky, who have helped me in innumerable ways with their friendship over the past several years.

I'd also like to thank my mother and the rest of my family, Allen, Ken, Steve, and Michael, because without them, nothing I've done would have been possible.

Ranjith Rajaram works as a Senior Principle Technical Support Engineer at a leading open source Enterprise Linux company. He started his career by providing support to web hosting companies and managing servers remotely. He has also provided technical support to their end customers. Early in his career, he has worked on Linux, Unix, and FreeBSD platforms.

For the past 12 years, he has been continuously learning something new. This is what he likes and admires about technical support. As a mark of respect to all his fellow technical support engineers, he has included developing software is humane but supporting them is divine in his e-mail signature.

At his current organization, he is involved in implementing, installing, and troubleshooting Linux environment networks. Apart from this, he is also an active contributor to the Linux container space, especially using Docker-formatted containers.

As a reviewer this is his second book. His earlier book was Learning RHEL Networking from Packt Publishing.

Amit Shah has been working on FOSS since 2001, and QEMU/KVM virtualization since 2007. He currently works as a senior software engineer in Red Hat. He has reviewed KVM Internals and Performance Tuning chapters.

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Preface

Mastering KVM Virtualization is a culmination of all the knowledge that we have gained by troubleshooting, configuring, and fixing the bug on KVM virtualization. We have authored this book for system administrators, DevOps practitioners, and developers who have a good hands-on knowledge of Linux and would like to sharpen their open source virtualization skills. The chapters in this book are written with a focus on practical examples that should help you deploy a robust virtualization environment, suiting your organization's needs. We expect that, once you finish the book, you should have a good understanding of KVM virtualization internals, the technologies around it, and the tools to build and manage diverse virtualization environments. You should also be able to contribute to the awesome KVM community.

What this book covers

Chapter 1, Understanding Linux Virtualization, talks about the prevailing technologies used in Linux virtualization and their advantages over others. It starts with basic concepts of Linux virtualization and advantages of Linux-based virtualization platforms and then moves on to hypervisor/VMM. This chapter ends with how Linux is being used in private and public cloud infrastructures.

Chapter 2, KVM Internals, covers the important data structures and functions which define the internal implementation of libvirt, qemu, and KVM. You will also go through the life cycle of vCPU execution and how qemu and KVM perform together to run a guest operating system in the host CPU.

Chapter 3, Setting Up Standalone KVM Virtualization, tells you how to set up your Linux server to use KVM (Kernel-based Virtual Machine) and libvirt. KVM is for virtualization and libvirt is for managing the virtualization environment. You will also learn how to determine the right system requirements (CPU, memory, storage, and networking) to create your own virtual environment.

Chapter 4, Getting Started with libvirt and Creating Your First Virtual Machines, will tell you more about libvirt and its supported tools, such as virt-manager and virsh. You will dig more into the default configurations available in libvirt. You will install a new virtual machine using virt-manager as well virt-install and also learn about advanced virtual machine deployment tools, such as virt-builder and oz.

Chapter 5, Network and Storage, is one of the most important chapters that teaches you about virtual networking and storage, which determine the QoS of your virtual machine deployments. In virtual networking, you will learn in detail about bridging, different bridging concepts, and the methods you can adopt for a fault tolerant network layer for virtual machines. You will understand how to segregate the network with the use of tagged vLan bridges. In storage, you will learn how to create storage pools for our virtual machines from storage backends such as fiber channel (FC), ISCSI, NFS, local storage, and so on. You will also learn how to determine the right storage backend for your virtual machines.

Chapter 6, Virtual Machine Lifecycle Management, discusses the tasks of managing virtual machines. You will learn about the different statuses of virtual machines and methods to access a virtual machine that includes spice and VNC. You will understand the use of guest agents. You will also learn how to perform offline and live migration of virtual machines.

Chapter 7, Templates and Snapshots, tells us how to create templates of Windows and Linux for rapid VMs provisioning. The chapter will also teach us how to create external and internal snapshots and when to use which snapshot. Snapshot management, including merge and deletion is also covered with snapshot best practice.

Chapter 8, Kimchi, An HTML5-Based Management Tool for KVM/libvirt, explains how to manage KVM virtualization infrastructure remotely, using libvirt-based web management tools. You will learn how to create new virtual machines, remotely adjust an existing VM's resource allocation, implement user access controls, and so on over the Internet using Kimchi WebUI. It also introduces VM-King, an Android application that lets you manage KVM virtual machines remotely from your Android mobile or tablet.

Chapter 9, Software-Defined Networking for KVM Virtualization, covers the use of SDN approach in KVM virtualization using Open vSwitch and supporting tools that include OpenDayLight SDN controller. You will learn about Open vSwitch installation and setup, creating vLans for KVM virtual machines, applying granular traffic and policy control to KVM VMs, creating overlay networks, and port mirroring and SPAN. You will also learn how to manage Open vSwitch using OpenDayLight SDN controller.

Chapter 10, Installing and Configuring the Virtual Datacenter Using oVirt, oVirt is a virtual datacenter manager and is considered as the open source replacement of VMware vCenter. It manages virtual machines, hosts, storage, and virtualized networks. It provides a powerful web management interface. In this chapter, we will cover oVirt architecture, oVirt engine installation, and oVirt node installation.

Chapter 11, Starting Your First Virtual Machine in oVirt, tells us how to initiate an oVirt datacenter in order to start your first virtual machine. This initialization process will walk you through creating a datacenter, adding a host to datacenter, adding storage domains, and its backend. You will learn about configuring networking.

Chapter 12, Deploying OpenStack Private Cloud backed by KVM Virtualization, covers the most popular open source software platform to create and manage public and private IaaS cloud. We will explain the different components of OpenStack. You will set up an OpenStack environment and will start your first instance on it.

Chapter 13, Performance Tuning and Best Practices in KVM, tells us how performance tuning can be done on a KVM setup. It will also discuss the best practices that can be applied in a KVM setup to improve the performance.

Chapter 14, V2V and P2V Migration Tools, will tell you how to migrate your existing virtual machines that are running on proprietary hypervisors to a truly open source KVM hypervisor using virt-v2v tool. You will also learn how to migrate physical machines to virtual machines and run them on the cloud.

Appendix, Converting a Virtual Machine into a Hypervisor, this will tell you how you can turn a VM into a hypervisor by using specific method.

What you need for this book

This book is heavily focused on practical examples; due to the nature of the content, we recommend that you have a test machine installed with Fedora 22 or later to perform the tasks laid out in the book. This test machine should have a minimum of 6 GB memory with an Intel or AMD processor that supports virtualization. You should be able to do most of the examples using nested virtual machines.

Who this book for

This book is for system administrators, DevOps practitioners and developers who have a good hands-on knowledge of Linux and would like to sharpen their skills of open source virtualization.

Conventions

In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: These ioctls() fundamentally map to the system KVM level, VM level, and vCPU level .

A block of code is set as follows:

switch (run->exit_reason) {

        case KVM_EXIT_IO:

              DPRINTF(handle_io\n);

                /* Called outside BQL */

              kvm_handle_io(run->io.port, attrs,

                            (uint8_t *)run + run->io.data_offset,

                          run->io.direction,

                           run->io.size,

                           run->io.count);

              ret = 0;

            break;

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

include/linux/kvm_host.h :

 

struct kvm {

      struct mm_struct *mm; /* userspace tied to this vm */

      struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];

 

      struct kvm_io_bus *buses[KVM_NR_BUSES];

      struct kvm_coalesced_mmio_ring *coalesced_mmio_ring;

}

Any command-line input or output is written as follows:

#git clone git://git.qemu-project.org/qemu.git

New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: If you want to connect to the remote hypervisor, check Connect to remote host and fill the details.

Note

Warnings or important notes appear in a box like this.

Tip

Tips and tricks appear like this.

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Chapter 1. Understanding Linux Virtualization

This chapter provides the reader with an insight into the prevailing technologies in Linux virtualization and their advantage over others. There are a total of 14 chapters in this book, which are lined up to cover all the important aspects of KVM virtualization, starting from KVM internals and advanced topics such as software defined networking, performance tuning, and optimization, to physical to virtual migration.

In this chapter, we will cover the following topics:

Linux virtualization and its basic concepts

Why you should use Linux virtualization

Hypervisor/VMM

What Linux virtualization offers you in the cloud

Public and private clouds

Tip

Before you start, check out the homepage of the book http://bit.ly/mkvmvirt to see the new updates, tips and version changes.

What is virtualization?

In philosophy, virtual means something that is not real. In computer science, virtual means a hardware environment that is not real. Here, we duplicate the functions of physical hardware and present them to an operating system. The technology that is used to create this environment can be called virtualization technology, in short, virtualization. The physical system that runs the virtualization software (hypervisor or Virtual Machine Monitor) is called a host and the virtual machines installed on top of the hypervisor are called guests.

Why should I use Linux virtualization?

Virtualization first appeared in Linux in the form of User-mode Linux (UML) and it started the revolution required to bring Linux into the virtualization race. Today, there is a wide array of virtualization options available in Linux to convert a single computer into multiple ones. Popular Linux virtualization solutions include KVM, Xen, QEMU, and VirtualBox. In this book, we will be focusing on KVM virtualization.

Openness, flexibility, and performance are some of the major factors that attract users to Linux virtualization. Just like any other open source software, virtualization software in Linux is developed in a collaborative manner; this indirectly brings users the advantages of the open source model. For example, compared to closed source, open source receives wider input from the community and indirectly helps reduce research and development costs, improves efficiency, and performance and productivity. The open source model always encourages innovation. The following are some of the other features that open source provides:

User-driven solutions for real problems

Support from the community and a user base who help fellow users to solve problems

Provides choice of infrastructure

Control of data and security, as the code is freely available to read, understand, and modify when required

Avoid lock-in flexibility to migrate the entire load with comparable product and stay free from vendor lock-in

Types of virtualization

Simply put, virtualization is the process of virtualizing something such as hardware, network, storage, application, access, and so on. Thus, virtualization can happen to any of the components.

Note

Refer to the Advantages of virtualization section for more details on different possibilities in virtualization.

For example:

SDN or Software-Defined Networking, https://en.wikipedia.org/wiki/Software-defined_networking. These techniques are examples of network virtualization, https://en.wikipedia.org/wiki/Network_virtualization.

Software Defined Storage (SDS), https://en.wikipedia.org/wiki/Software-defined_storage. This is part of storage virtualization, https://en.wikipedia.org/wiki/Storage_virtualization.

The application streaming, remote desktop service, and desktop virtualization techniques fall into the category of application virtualization, https://en.wikipedia.org/wiki/Application_virtualization.

However, in the context of our book, we will discuss virtualization mainly in terms of software (hypervisor-based) virtualization. From this angle, virtualization is the process of hiding the underlying physical hardware so that it can be shared and used by multiple operating systems. This is also