It is not possible for a client (front end) to record directly, the server is the only one that can record.
The only way to get separate storage per user is to set up multiple servers: one per user.
It may be possible to use a powerful enough machine to run both the server and a client to get a somewhat one-box solution for one user. Something like an NVidia Shield may be able to do it. I don't have one so I can't tell for sure.
There are a couple of people around these forums who have a setup with multiple servers. I'm sure they can provide more details about their setups.