Now that the first two chapters have addressed at a high level the basic questions of why you need high availability and how to achieve it, it is time to delve into the world of technology. It is not enough to consider technology and high availability from a Microsoft SQL Server standpoint only ”you must also consider the operating system, which is Microsoft Windows. Without Windows there is no SQL Server. This chapter helps you to make an informed decision by providing a basic understanding of the high availability technologies used throughout this book. The following technologies are discussed:
Windows Clustering, which includes:
Network Load Balancing clusters
Geographically dispersed clusters
Microsoft SQL Server 2000, which includes:
Backup and restore
The word cluster describes clustered servers, clustered indexes for databases, and more. As you can see from the preceding list, clustering is involved in many of the options discussed in this chapter. This chapter standardizes the terminology and helps you distinguish between the different types of clusters for the rest of the book.
One thing this chapter and this book will not do is to give you a decision tree and point to one right answer. Two words govern high availability solution decisions ” it depends . High availability is not a clear-cut concept, but one that involves a lot of ambiguity.