CentOS High Availability

Table of Contents

CentOS High Availability

Credits

About the Author

About the Reviewers

www.PacktPub.com

Support files, eBooks, discount offers, and more

Why subscribe?

Free access for Packt account holders

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Errata

Piracy

Questions

1. Getting Started with High Availability

What is high availability?

System design

Computer clusters

High-availability solutions

Summary

2. Meet the Cluster Stack on CentOS

Cluster stack software

The cluster communication layer

The cluster messaging and membership service

Quorum

The cluster resource management layer

A theoretical cluster service example

Cluster stack on CentOS Linux

Preparing for cluster stack software installation

Summary

3. Cluster Stack Software on CentOS 6

Cluster infrastructure

Cluster operating system preparation

Installing and configuring Corosync

Installing and configuring CMAN

Installing and configuring RGManager

Summary

4. Resource Manager on CentOS 6

Working with RGManager

Configuring failover domains

Adding cluster resources and services

Resources

Services

Managing cluster services

Removing cluster resources and services

Summary

5. Playing with Cluster Nodes on CentOS 6

Adding a new cluster node

Removing a cluster node

Summary

6. Fencing on CentOS 6

Fencing

Fencing configuration

APC switch fencing

IPMI management board fencing

HP iLO management board fencing

Fencing test

Fence master node

Fence check

Fence node

Summary

7. Testing Failover on CentOS 6

Hardware failure

Network failure

Summary

8. Two-node Cluster Considerations on CentOS 6

Quorum in a two-node cluster

Two-node cluster configuration

Quorum disk

Summary

9. Cluster Stack Software on CentOS 7

Cluster infrastructure

Cluster operating system preparation

Network configuration

NTP configuration

DNS configuration

Installing and configuring Corosync

Installing and configuring Pacemaker

Summary

10. Resource Manager on CentOS 7

Working with pcs

Adding cluster resources, constraints, and resource groups

Configuring resources

Configuring resource constraints

Configuring resource groups

Managing resources

Moving resources around

Stopping resources

Starting resources

Banning resources

Clearing resource constraints

Removing cluster constraints, resource groups, and resources

Removing resource constraints

Removing resource groups

Removing resources

Summary

11. Playing with Cluster Nodes on CentOS 7

Adding a new cluster node

Cluster node standby mode

Removing a cluster node

Summary

12. STONITH on CentOS 7

Fencing

Configuring fence devices

APC switch fencing

IPMI management board fencing

HP iLO management board fencing

Fence test

Summary

13. Testing Failover on CentOS 7

Hardware failure

Network failure

Summary

14. Two-node Cluster Considerations on CentOS 7

Quorum in a two-node cluster

Two-node cluster configuration

Summary

Index

CentOS High Availability

CentOS High Availability

Copyright © 2015 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.

Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.

Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.

First published: April 2015

Production reference: 1220415

Published by Packt Publishing Ltd.

Livery Place

35 Livery Street

Birmingham B3 2PB, UK.

ISBN 978-1-78528-248-5

www.packtpub.com

Credits

Author

Mitja Resman

Reviewers

Denis Fateyev

Christophe Grenier

Commissioning Editor

Veena Pagare

Acquisition Editor

Reshma Raman

Content Development Editor

Neeshma Ramakrishnan

Technical Editor

Abhishek R. Kotian

Copy Editor

Vikrant Phadke

Project Coordinator

Danuta Jones

Proofreaders

Stephen Copestake

Safis Editing

Paul Hindle

Indexer

Rekha Nair

Production Coordinator

Melwyn D'sa

Cover Work

Melwyn D'sa

About the Author

Mitja Resman hails from a small, beautiful country called Slovenia in south-central Europe. He is a fan of Linux and also an open source enthusiast. He is a Red Hat Certified Engineer and Linux Professional Institute professional. Working as a system administrator, Mitja gained years of professional experience with open source software and Linux system administration on local and international projects. The Swiss Army Knife syndrome makes him an expert in the field of VMware virtualization, Microsoft system administration, and more recently, Android system administration.

Mitja has a strong desire to learn, develop, and share knowledge with others. This is the reason he started a blog called GeekPeek.Net. It provides CentOS Linux guides and how-to articles covering all sorts of topics appropriate for both beginners and advanced users. Mitja is also a devoted father and husband. His daughter and wife are the ones who take his mind off the geek stuff and make him appreciate life and look forward to the things to come.

I would like to thank my wife for putting up with my late night writing sessions and for all the support I got when I decided to write this book. I would also like to thank all of my family for the words of encouragement at the time of writing this book. Also, a special thanks to my friend who introduced me to Linux many years ago.

About the Reviewers

Denis Fateyev holds a Master's degree in Computer Science, and has been working with Linux for more than 10 years, mostly with Red Hat and CentOS. He currently works as a Perl programmer and a DevOps for a small German company. Being a keen participant in the open source community, he is a package maintainer in the Fedora and Repoforge projects. Foreign languages (German and Spanish) and linguistics are also his passion.

Denis can be reached at <[email protected]>.

Christophe Grenier holds a diploma from ESIEA Graduate School of Engineering, and is the director of operations at Global SP—a French IT service provider. He has more than 15 years of experience in Red Hat Linux systems. He uses the Corosync cluster solution from CentOS 5 onwards. Christophe teaches several courses about Linux and IT Security in Sécurité de l'Information et des Systèmes at ESIEA Mastère Spécialisé. He is also known for the open source data recovery utilities, TestDisk, and PhotoRec.

www.PacktPub.com

Support files, eBooks, discount offers, and more

For support files and downloads related to your book, please visit www.PacktPub.com.

Did you know that Packt offers eBook versions of every book published, with PDF and ePub files available? You can upgrade to the eBook version at www.PacktPub.com and as a print book customer, you are entitled to a discount on the eBook copy. Get in touch with us at for more details.

At www.PacktPub.com, you can also read a collection of free technical articles, sign up for a range of free newsletters and receive exclusive discounts and offers on Packt books and eBooks.

https://www2.packtpub.com/books/subscription/packtlib

Do you need instant solutions to your IT questions? PacktLib is Packt's online digital book library. Here, you can search, access, and read Packt's entire library of books.

Why subscribe?

Fully searchable across every book published by Packt

Copy and paste, print, and bookmark content

On demand and accessible via a web browser

Free access for Packt account holders

If you have an account with Packt at www.PacktPub.com, you can use this to access PacktLib today and view 9 entirely free books. Simply use your login credentials for immediate access.

Preface

The book will guide you through the process of installing, configuring, and administering a multinode computer cluster on CentOS version 6 and 7 using two different cluster suites with respect to the CentOS version.

What this book covers

Chapter 1, Getting Started with High Availability, provides facts about high availability.

Chapter 2, Meet the Cluster Stack on CentOS, shows you how cluster stack software works as a whole to provide high availability.

Chapter 3, Cluster Stack Software on CentOS 6, covers installation and configuration of cluster stack software on CentOS 6.

Chapter 4, Resource Manager on CentOS 6, teaches you how to manage your cluster resources and services with the RGManager resource manager on CentOS 6.

Chapter 5, Playing with Cluster Nodes on CentOS 6, explains how to manage and administer cluster nodes on CentOS 6.

Chapter 6, Fencing on CentOS 6, provides the details and recommendations on the quorum disk on CentOS 6.

Chapter 7, Testing Failover on CentOS 6, discovers cluster node fencing on CentOS 6.

Chapter 8, Two-node Cluster Considerations on CentOS 6, covers some final cluster failover tests on CentOS 6.

Chapter 9, Cluster Stack Software on CentOS 7, shows you how to install and configure cluster stack software on CentOS 7.

Chapter 10, Resource Manager on CentOS 7, teaches you how to manage your cluster resources and services with the Pacemaker resource manager on CentOS 7.

Chapter 11, Playing with Cluster Nodes on CentOS 7, explains how to manage and administer cluster nodes on CentOS 7.

Chapter 12, STONITH on CentOS 7, introduces the details and recommendations on quorum disk on CentOS 7.

Chapter 13, Testing Failover on CentOS 7, covers cluster node fencing, the so-called STONITH, on CentOS 7.

Chapter 14, Two-node Cluster Considerations on CentOS 7, provides some final cluster failover tests on CentOS 7.

What you need for this book

To closely follow the guides provided in this book, three virtual or physical machines with a working CentOS version 6 or 7 installation are required. The machines must have Internet connectivity to provide successful software installation, and local network connectivity to provide normal cluster operation.

Who this book is for

This book is targeted at system engineers and system administrators who want to upgrade their knowledge and skills in high availability, and want to learn how to practically achieve high availability with CentOS Linux. You are expected to have good knowledge of CentOS Linux and basic networking experience.

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: If you want to change this, edit the NTP configuration file in /etc/ntp.conf.

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

[root@node-1