Q: How can I tell how much memory SQL Server 2008 is using?

A: There are several performance counters that can be used to evaluate how much memory SQL Server 2008 is using and is allowed to use.

Start Performance Monitor and add these counters:

SQL Server:Memory Manager - Total Server Memory (KB) and SQL Server:Buffer Manager - Total pages show the same value—one is in pages, so multiply the Total pages number by 8 (page size of 8KB) to get the actual memory, which should be the same value as Total Server Memory (KB).