Here’s a pointer to a Microsoft Knowledge base article on Hyper-v Dynamic Memory not working on Windows 2008 Standard & Web edition Hotfix: Hyper-V Dynamic Memory does not work on a Windows Server 2008 Standard Edition or Windows Web Server 2008 virtual machine (VM) As you probably already know you have a similar issue with Window 2008 R2 Standard and Web edition virtual machines which is fixed by installing SP1 in the guest. For the predecessor of R2 you need to install this hotfix.
The cause is that on these versions of the operating systems the the required memory enlightenment is supported. After installing the hotfix (or SP1 in the case of Windows 2008 R2) memory addition enlightenment is available on these SKU and your good to go.
After an initial false start (https://blog.workinghardinit.work/2011/01/14/windows-2008-r2-windows-7-sp1-rtm-today/) Window 2008 R2/Windows 7 Service Pack 1 has been officially RTMed today . SP1 brings Dynamic Memory& RemoteFX to hyper-V virtualization. I’m probably doing a SQL Server virtualization project and thus I’m very interested in the ability to disable NUMA spanning (watch Ben Armstrong’s Tech Ed 2010 presentation here) http://blogs.msdn.com/b/virtual_pc_guy/archive/2010/06/10/talking-about-dynamic-memory-the-movie.aspx) when beneficial to do so . Which is good news. Until now SQL Server Hyper-V host where better of using machine with lesser CPU sockets & and SSL server VM’s that don’t consume more RAM than that CPU socket can address directly to avoid this. Until now, for the environment at hand, I’m leaning to virtualizing SQL Server on it’s own Hyper-V cluster for that reason. It will have to be confirmed in a test environment to see how big the impact is. Systems do differ and get better every year. Perhaps I’ll get back to that subject later. Anyway The bits should be on TechNet/MSDN on February 16th 2001 and available to the general public on February 22 2011. Read the announcement by Microsoft here Windows Server 2008 R2 and Windows 7 SP1 Releases to Manufacturing Today