Book Image

Professional SQL Server High Availability and Disaster Recovery

By : Ahmad Osama
Book Image

Professional SQL Server High Availability and Disaster Recovery

By: Ahmad Osama

Overview of this book

Professional SQL Server High Availability and Disaster Recovery explains the high availability and disaster recovery technologies available in SQL Server: Replication, AlwaysOn, and Log Shipping. You’ll learn what they are, how to monitor them, and how to troubleshoot any related problems. You will be introduced to the availability groups of AlwaysOn and learn how to configure them to extend your database mirroring. Through this book, you will be able to explore the technical implementations of high availability and disaster recovery technologies that you can use when you create a highly available infrastructure, including hybrid topologies. Note that this course does not cover SQL Server Failover Cluster Installation with shared storage. By the end of the book, you’ll be equipped with all that you need to know to develop robust and high performance infrastructure.
Table of Contents (9 chapters)
Professional SQL Server High Availability and Disaster Recovery
Preface

Understanding Transactional Replication


In this section, we'll look at how transactional replication works. The following diagram describes how transactional replication works:

Figure 2.1: Transactional replication example

This diagram shows the AdventureWorks database being replicated using transactional replication. Once transactional replication is configured, the snapshot agent, log reader agent, and distribution agent are created as part of the replication. The agents then work together, as described here, to replicate the transactions.

The snapshot agent is used once to initialize the subscriber database schema with that of the publisher. This isn't shown in the diagram, however, it's the first thing that happens when the transactional replication starts.

The subscriber database can be initialized using the publisher database backup, which is covered later in this lesson.

Once initialized, the transactions are replicated as follows:

  • Steps 1 and 2: The log reader agent continuously scans...