I have a 64-bit Windows Server 2008 R2 Standard O/S, installed as a virtual platform. The O/S reports that it has 12Gb of RAM installed - I don't know how much RAM the physical box has available to it.
The platform is used as a dedicated db server, running Microsoft SQL Server 2008 R2.
The db hosts 2x databases - a test db and a prod db, both for the same application.
The same application is also running on a separate db server, which is not virtualized. That server is running 64-bit Windows Server 2003 R2 Standard editition, SP 2. That box has 8Gb of RAM installed and is running a 64-bit version of Microsoft SQL Server 2005. Again, its a dedicated db server and runs a PROD and TEST instance of the same db.
The problem that I have is that the 2008 platform needs to be re-started at regular intervals because it consumes all the memory - literally within a few days. The 2005 platform hasn't been rebooted in years and consistently reports that approximately 8.5GB is being consumed. So I don't believe its the application which is consuming the memory - indeed, no additional software has been installed on either db server. In both cases, it is just the O/S + SQL Server.
When I re-start the MS SQL Server service on the 2008 box, the memory reduces from about 11.7Gb down to about 1.5Gb but as I say, within a few days its back up to 11.5+ GB.
When it closes in on the 12Gb limit, the box becomes unresponsive via remote desktop and starts to throw error message in SQL work sheets.
One issue which may or may not be related. On the 2005 platform, I have a maintenance plan which does a daily full backup & backs up the transaction log every hour. This works fine on the 2005 box but is also set up on the 2008 and has never worked.