Jeffrey Williams (8/19/2009)
SQL Server will only release memory back to the OS when the OS needs that memory. On dedicated SQL Server machines - that will never occur. If you have a max memory defined, SQL Server will not take more than the max memory setting for the buffer pool - but does take more than that, just not a lot more.I have never seen SQL Server ever release memory once it has allocated it, and I wouldn't want it to - because databases perform much better with a lot of memory.
Several incorrect statements there. It can occur on a SQL Server only box that the OS asks for memory back. Also SQL Server does give memory back, and you DO want it to or else your server could suffer incredibly bad performance or even literrally stop execution if the OS has a need for RAM that cannot be served.
Best,
Kevin G. Boles
SQL Server Consultant
SQL MVP 2007-2012
TheSQLGuru on googles mail service