The term High Availability means that the servers or systems that host or run the business-critical applications should be highly available 24 X 7. As the word itself defines how important it is to make these applications and data available for end-users as well as business users, if this data is not available for a short time, it will be a big problem for both sets of users. Imagine a bank spread across the country and having a huge customer base. One fine day, their server crashes! If the bank relies only on backups, then it might end up losing approximately 15 to 30 minutes of data, depending on the backup strategy. However, the HA options related to SQL Server such as clustering, replication, log shipping, and database mirroring will help overcome this situation.
By the end of the book, you will be able to find yourself in a position where you can easily install and configure the different High Available solutions for SQL Server. You will also be able to troubleshoot most common issues yourself by following the troubleshooting appendix.
Chapter 1, Understanding Windows Domains, Domain Users, and SQL Server Security, will help you understand what is Windows domain, what are domain users, and the basic security concepts for Windows and SQL Server to get yourself prepared for the next chapter.
Chapter 2, Implementing Clustering, will help you understand the prerequisites for SQL Server Clustering and guide you on how to install and configure SQL Server Cluster using both T-SQL and SSMS. The chapter also helps you on how to add or remove a node from an existing cluster.
Chapter 3, Snapshot Replication, will help you understand prerequisites for installing Snapshot Replication using SQL Server. It guides you in installing and configuring Snapshot Replication using both T-SQL and SSMS.
Chapter 4, Transactional Replication, will give you information on how to install and configure Transactional Replication. It also helps you understand how replication works and the different options available to configure and install Transactional Replication.
Chapter 5, Merge Replication, helps you install and configure Merge Replication. It also makes you understand the different components of Merge Replication, and how it works. It guides you on how to configure Merge Replication, using both T-SQL and SSMS.
Chapter 6, Peer-to-Peer Replication, explains how to install and configure Peer-to-Peer Replication, using both T-SQL and GUI. It also explains how to add or remove nodes.
Chapter 7, Log Shipping, describes what Log Shipping is, how it works, and what are the prerequisite components for its installation. The chapter also helps understand how to install Log Shipping using both T-SQL and SSMS.
Chapter 8, Database Mirroring, explains what Database Mirroring is all about, how it works, and what are the different components we need to implement it. We also learn different types of Database Mirroring and how to install and configure it using both T-SQL and SSMS.
Appendix A, Troubleshooting, contains the troubleshooting tips for the common issues faced in all of the previous chapters.
Appendix B, External References, contains the external references that we might need to refer, in order to gain further information on topics covered in all of the previous eight chapters.
High Availability options can be used to make systems or servers highly available, so that the work isn't hindered in case of any emergency or failure of resources. So, to make your system and server capable of installing SQL Server 2008 High availability options such as clustering, replication, database mirroring, and log shipping, the following are the prerequisites:
Processor type: Pentium-3 or higher.
Processor speed: 1.0 Gigahertz or higher.
RAM: At least 512 MB, but 2 GB is recommended.
Display: VGA or higher resolution.
Operating system: Windows 7 Ultimate, Windows Server 2003 (x86 or x64) , Windows Server 2008 (x86 or x64).
Disk space: Minimum 1 GB.
.NET framework.
Windows Installer 4.5 or later.
Microsoft Data Access Component (MDAC) 2.8 SP1 or later. MDAC can be obtained from
For complete information on prerequisites, a reader can refer to the prerequisites section of each chapter.
You may refer to the external references for the further reading and can post back your queries to any SQL Server forums out their such as http://www.sql-server-performance.com or www.surat-user-group.org/forums.
If you are a SQL Server Developer, or a System Administrator, or even a novice DBA, then this book is for you. It requires you to have only a basic understanding of how SQL Server works to get you through the installation of SQL Server HA.
In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.
Code words in text are shown as follows: "We should set the value as true for the @stream_blob_columns of sp_addmergearticle parameter if there are LOB data types to publish."
A block of code is set as follows:
use [ReportServer$SQL2008R2] execsp_replicationdboption @dbname =N'ReportServer$SQL2008R2', @optname =N'merge publish',
Any command-line input or output is written as follows:
/SQLSVCPASSWORD="XYZ12345"
/AGTSVCACCOUNT="SSCitation\sqlagent"
/AGTSVCPASSWORD="XYZ12345"
New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "In the Snapshot Agent dialog box, check the Create a snapshot immediately option to apply it to the subscriber immediately."
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