CacheFiles when the cached system is unmounted, or alternatives

In my current setup, I have two machines serverA and serverB in different geographical areas. serverA has a limited amount of persistent memory (~256GB), while serverB can be considered to have enough that I will never use it all up (several TB). serverA has a directory /data which is an NFS share from serverB, and also has CacheFiles enabled. This setup achieves the following: 1. replication: if serverA's disk die, I can still recover the data from serverB 2. unlimited memory: I am not limited by serverA's small amount of persistent memory 3. fast access to data: the content of /data that is in the cache (basically the most recently accessed 200GB) can be accessed without a round-trip on the network Note that a simple backing-up setup would not achieve 2. I'd like to achieve 1., 2. and 3. but also the following: 4. robustness: if serverB goes down temporarily, serverA can still work with the data that's been cached, without me having to manually intervene on serverA 5. encryption: /data is encrypted by serverA, so that someone with access to serverB cannot access the data I'm mostly interested in 4. and 5. would only be a bonus. Here are my questions: - I suppose CacheFiles does not achieve 4., is this correct? - What are the simplest setups that would allow me to achieve 1., 2., 3. and 4., and possibly also 5.?