I'm responsible for a file server with about 5 terrabytes of data. The file server is based on Windows 2008 R2. I've noticed extreme memory usage on the server. After a reboot, it slowly builds up until almost all RAM memory is consumed.
So I googled around and found this post and it turned out I had the same exact issue.
I've confirmed with the tool 'RAMmap' that NTFS metadata is the issue. Microsoft also created a blog post about this.
The author of the first article resolved the issue by adding more RAM memory. But with 16 GB already assigned, I was not to happy to add more memory to the virtual file server, eating away on the RAM resources of our virtualisation platform.
I could never find a root cause of the issue. In that case, you need to obtain the 'Microsoft Windows Dynamic Cache Service'. This application allows you to configure how large the medata caching may grow.
Please note that this services is not a next-next-finish installation. Follow the included Word document with instructions carefully and configure a sane memory setting for your server. I limited the cache to half the RAM available to the server and this works out well.