We have a Windows Server 2008R2 server with 32GB of RAM, and ~1,000,000 file system objects across 15Tb of storage. The utilization is very low (only supporting 2 developers) so keeping the file contents cached (Mapped File) is not at all important, but quick access to file metadata (Metafile) IS important. The server behaviour seems to be the exact opposite. Mapped File allocation expands to use all available memory, while the Metafile appears to be frequently purged.
Example - After querying properties (Select root folders -> Properties) the Metafile allocation raises to ~750Mb (great!). However, when I do the same an hour or two later, the metadata allocation has fallen to ~300MB and a full disk rescan occurs (1-2 minutes, not great!).
How do I keep the Metafile contents cached?
RamMap output graphic is here - http://i.imgur.com/X1EOskf.jpg