Ask DBAs what their most dreaded situation would be. You will find they are very cautious in their production environments. For most people it would be the fear of production servers failing. A seasoned organization always performs mock drills to simulate disasters and they failover to the DR (Disaster Recovery) site to check their infrastructure resilience. It is a very common practice to perform these types of drills. There are documents DBAs have called recovery procedures which are used by the team. SQL Server 2012 brought in some great new features and one of the important ones is scalability and performance via AlwaysOn. AlwaysOn is a superset feature and is a combination of many things you will learn about. As the language suggests, this technology achieves a SQL Server infrastructure that can be "always on". For businesses that run 24x7 downtime means the loss of business. This type of risk is out of the question for these businesses. This book discusses in detail the concepts of SQL Server AlwaysOn starting from the basics.