My thesis at university is studying about high availability database. Can you suggest me some good books on this field? I want to concentrate on SQL Server.
Gray and Reuter's Transaction Processing: Concepts and Techniques is quite a good book on the underlying theory. It has quite a lot of background reading on fault tolerance (one of the authors used to work for Tandem) and other related items. Fairly dry and textbook-ish, but arguably the definitive work on the subject.
Allan Hirt is a notable person in SQL Server area specializing in High Availability and wrote an excellent book on this topic.
SQLPass.Org is a free website and you can find few videos from industry experts on this topic as well.
Paul Randal managed SQL Server team and he has some excellent posts on this topic as well. http://sqlskills.com/BLOGS/PAUL/category/High-Availability.aspx
And finally few good white papers on this topic at http://technet.microsoft.com/en-us/library/ee229552%28SQL.10%29.aspx