Hi - I know how to determine the total memory used by the server. I know how to determine the total memory used by SQL Server. I know how to confirm the total memory used by SQL Server only by looking at the buffer cache memory. I know how to see how much memory is being used by sql server outside of the maximum sql server memory allocation i.e. non-buffer cache memory usage for sql. the only way I determine how much memory the operating system is using is subtracting the sql server memory (buffer cache) and the sql server memory outside max server memory allocation (non-buffer cache) from total server memory usage (assuming on sql server is on the server). Is there a performance counter to confirm how much memory the actual operating system uses and only the operating system uses? This will help confirm the sql server memory allocation (buffer cache and non-buffer cache).