Book Image

High Availability MySQL Cookbook

By : Alexander Davies
Book Image

High Availability MySQL Cookbook

By: Alexander Davies

Overview of this book

High Availability is something that all web sites hope to achieve, especially those that are linked to big companies.MySQL, an open source relational database management system (RDBMS), can be made highly available to protect from corruption, hardware failure, software crashes, and user error. Running a MySQL setup is quite simple. Things start getting complex when you start thinking about the best way to provide redundancy. There are a large number of techniques available to add 'redundancy' and 'high availability' to MySQL, but most are both poorly understood and documented.This book will provide you with recipes showing how to design, implement, and manage a MySQL Cluster and achieve high availability using MySQL replication, block level replication, shared storage, and the open source Global File System (GFS).This book covers all the major techniques available for increasing availability of your MySQL databases. It demonstrates how to design, implement, troubleshoot and manage a highly available MySQL setup using any one of several techniques, which are shown in different recipes. It is based on MySQL Cluster 7.0, MySQL (for non clustered recipes) 5.0.77, and CentOS / RedHat Enterprise Linux 5.3.The book starts by introducing MySQL Cluster as a technology and explaining how to set up a simple cluster. It will help you to master the options available for backing up and restoring a file in the MySQL Cluster. By following the practical examples in this book, you will learn how to manage the MySQL Cluster. Further, we will discuss some troubleshooting aspects of the MySQL Cluster.We also have a look at achieving high availability for MySQL databases with the techniques of MySQL Replication, block level replication, shared storage (a SAN or NAS), and DRBD.Finally, you will learn the principles of Performance tuning and tune MySQL database for optimal performance.
Table of Contents (17 chapters)
High Availability MySQL Cookbook
Credits
About the Author
About the Reviewers
Preface
Base Installation
Index

Using LVM to reduce downtime on a master when bringing a slave online


It is possible to use the Logical Volume Manager (LVM) which comes with most Linux distributions, including Redhat / CentOS, to take a read-only snapshot of the block device that the MySQL Data directory is residing on, and use this to synchronize a slave with only a very short period of table locks on the master.

In many cases of 24x7 use of a database, this is essential and it can be useful when you do not want to wait for a scheduled outage interval every time a slave needs re-synchronizing.

Getting ready

For the purpose of this recipe, we will require that you already have the MySQL data directory residing on a volume group with enough free space to hold the data that will change during the time the backup is running (perhaps, 10-20% for a very busy server).

In order to check if you have space in a volume group, use the vgs command:

[root@node2 mysql]# vgs
  VG     #PV #LV #SN Attr   VSize  VFree
  system   1   2   0...