32-bit memory addressing is often limiting for performance-critical and memory-intensive enterprise applications that support thousands of concurrent users and run very complex queries. If memory bottlenecks are identified, one option to tackle performance and scalability issues is to add more RAM and enable AWE. However, as discussed in this chapter, AWE has some limitations, and the only way to gain performance and scalability in such situations is to consider moving to 64-bit computing. In addition to being used in memory-constrained scenarios, 64-bit systems are also being used in other scenarios, such as for server consolidation, data warehouse applications, Unix migration, and implementing ERP and CRM solutions.
This chapter begins with an introduction to 64-bit computing, including its benefits and a description of scenarios in which the 64-bit architecture can be helpful. The second part of the chapter describes SQL Server 2005's support for 64-bit systems. SQL Server 2005 natively supports Itanium and x64 platforms and fixes a lot of the limitations of SQL Server 2000 (64-bit).