Is there a safe way to configure how much memory exchange, or SQL server for that matter, can use on an SBS server? We upped our memory to 8Gb and it's using 7.8Gb consistently.
Exchange: there is a registry key. At leat was in 2003.
Sql: standard setting in server properties. Connect using Sql manager, set it.
THat said, it is normal - both exchange and sql use up all memory. This is expected behavior. What is your problem of them using memory that is available? the problems start when tehy use MORE than the 8gb.
Exchange 2007 is pretty aggressive about using available memory for caching; this is normal. You can pretty much expect that a mailbox server that's serving users will gravitate toward 95% memory utilization. There's a good technet blog article about this behavior here.