Why not just modify the Redis code to modularize the server part, and define a user friendly API? It seems like a waste to re-implement all of the data structures, since they will eventually do exactly the same thing.
From the quick glance over the source code, it seems that this implementation has this assumption too. (I may be wrong, though - it is possible I've missed something.)
On the other hand, Redis has "VM" thing, which allows larger-than-memory databases by swapping less frequently used data to disk.
This seems like a bad case of NIH syndrome.