Book Image

Microsoft SQL Server 2008 High Availability

By : Hemantgiri S. Goswami
Book Image

Microsoft SQL Server 2008 High Availability

By: Hemantgiri S. Goswami

Overview of this book

<p>Every business has it's mission critical applications and data. Therefore, it is very important to keep database servers up and running all the time – 24 X 7. There is a need to store and process terabytes of data to cater for business needs, and it is vital to make data highly available.<br /><br />High availability is all about the site being accessible all the time. High availability solutions minimize the downtime for these mission critical applications.</p> <p>Microsoft SQL Server is a powerful relational database engine, widely used to store and maintain data in Enterprises of various levels be they small, medium or large.</p> <p>This book will teach you how best to use these readily-available options and save you time in making your websites highly available.<br /><br />This Microsoft SQL Server 2008 High Availability book will take you through pre and post installation concepts and common issues you come across while working with SQL Server HA. It will teach you how these various HA solutions can be installed using GUI and the command line. It will also show you how to troubleshoot common issues you may encounter whilst installing or managing the HA option in your environment. It provides references to external links for more advanced learning on the topic.<br /><br />This book starts with an introductory chapter into the windows domain, domain users and various handshake methods available with Windows server. It also offers information the different authentication methods available with SQL Server - giving you an insight into the importance of security. After you are through with the security aspects, your journey to installing SQL Server HA will start. It will cover the concepts of database mirroring, log shipping, clustering, and replication.<br /><br />By the end of this book you will be confident enough to take up the challenge to install any of the SQL Server HA options.</p>
Table of Contents (18 chapters)
Microsoft SQL Server 2008 High Availability
Credits
Foreword
About the Author
Acknowledgement
About the Reviewers
www.PacktPub.com
Preface

How replication works


In the diagram under the Components of the replication section at the Publisher end, we can see that all the data marked for replication is either pulled or pushed at the Distributor database, which later is pulled at or pushed by at the Subscriber end. Now, all this work has to be done on a continuous or a scheduled interval, based on the company policy. The process of replication creates some agents whose work is to send and receive data. There are different types of replication agents for different types of replications. Let's go through each of them, although we will have detailed information on each of them in a separate chapter.

  • Snapshot Agent: The Snapshot Agent is typically used with all types of replication. The Snapshot Agent's work is to prepare schema and initial data files of the published tables and other objects like stored procedures. Snapshot Agent runs at the Distributor end.

  • Log Reader Agent: Log Reader Agent is used with Transactional Replication...