Q: What was the memory change in Windows Server 2012 R2 related to CSV cache?

A: In Windows Server 2012, the CSV cache could be set to up to 20 percent of the system memory only. In Windows Server 2012 R2, the CSV cache can be set to up to 80 percent of the system memory.

The ability to set such a large cache is aimed at scale-out file servers where committing more memory to cache will result in great performance gains. For Hyper-V clusters, typically it's better to have memory available to virtual machines (VMs) while some CSV cache will help overall performance.