Why use SQL?
Once you start running multiple web servers for the same web site, the default asp.net session state, InProc, is no longer useful, as you cannot guarantee that each page request goes to the same server. It becomes necessary to have a central state store that every web server accesses.
SQL Server offers you centralized storage of a session state in a Web farm. It also offers the transactional capabilities that provide reliability to most relational database systems. You can use SQL Server to save a session. This process is not as efficient as InProc and StateServer mode, because you must store the information in a different process or on a different server. However, this option may be more efficient than using the aspnet_state service, depending on the actual workload and the database configuration. Once you start saving session state to a SQL database it will also persist through web server restarts and reboots.
For reliability you should consider storing session state for a web farm on a SQL cluster.
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Thanks & Regards
Lakhan Pal Garg
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