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CentOS High Availability

By : Resman

4.5 (12)

CentOS High Availability

4.5 (12)

By: Resman

Overview of this book

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 practically how to achieve high availability with CentOS Linux. You are expected to have good CentOS Linux knowledge and basic networking experience.

Preface

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Free Chapter

1. Getting Started with High Availability

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

2. Meet the Cluster Stack on CentOS

Cluster stack software

The cluster communication layer

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

3. Cluster Stack Software on CentOS 6

Cluster infrastructure

Cluster operating system preparation

Installing and configuring Corosync

Installing and configuring CMAN

Summary

4. Resource Manager on CentOS 6

4. Resource Manager on CentOS 6

Working with RGManager

Configuring failover domains

Adding cluster resources and services

Managing cluster services

Removing cluster resources and services

Summary

5. Playing with Cluster Nodes on CentOS 6

5. Playing with Cluster Nodes on CentOS 6

Adding a new cluster node

Removing a cluster node

Summary

6. Fencing on CentOS 6

6. Fencing on CentOS 6

Fencing

Fencing configuration

IPMI management board fencing

HP iLO management board fencing

Fencing test

Summary

7. Testing Failover on CentOS 6

7. Testing Failover on CentOS 6

Hardware failure

Network failure

Summary

8. Two-node Cluster Considerations on CentOS 6

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

9. Cluster Stack Software on CentOS 7

Cluster infrastructure

Installing and configuring Corosync

Summary

10. Resource Manager on CentOS 7

10. Resource Manager on CentOS 7

Working with pcs

Adding cluster resources, constraints, and resource groups

Managing resources

Removing cluster constraints, resource groups, and resources

Summary

11. Playing with Cluster Nodes on CentOS 7

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

12. STONITH on CentOS 7

Fencing

Configuring fence devices

IPMI management board fencing

HP iLO management board fencing

Fence test

Summary

13. Testing Failover on CentOS 7

13. Testing Failover on CentOS 7

Hardware failure

Network failure

Summary

14. Two-node Cluster Considerations on CentOS 7

14. Two-node Cluster Considerations on CentOS 7

Quorum in a two-node cluster

Two-node cluster configuration

Summary

Index

Index

Quorum disk

The second solution to the quorum problem in a two-node cluster configuration is to implement an additional quorum disk. A quorum disk is a shared storage block device both cluster nodes have access to. The Cluster and cluster nodes use this disk as cluster configuration storage and also as a secondary heartbeat communication channel. A quorum disk brings another vote to the cluster configuration, therefore eliminating the problem of a two-node cluster configuration quorum. A quorum disk can also be used as a secondary cluster heartbeat communication channel, and can therefore resolve cluster split-brain situations in the case of network communication failure.

With the quorum disk implemented, in the event of a cluster node failure quorum is reached by one cluster node vote and one quorum disk vote, and the cluster can continue to perform its normal operation.

Tip

The quorum disk solution is not reserved specifically for a two-node cluster configuration. It can be used as an additional...

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