What are the precautions by which SQLSERVER Mode work properly
Following are the things to keep in mind so that the SQLSERVER Mode works properly:-
A) In the SQLSERVER mode, session data is stored in a different method so you must ensure that your objects are serializable.
b) The IIS metabase (\LM\W3SVC\2) must be identical across all the servers in that farm.
c) By default Session objects are stored in "Tempdb", you can configure it and store outside "TempDB" by running Microsoft provided by SQL script.