Yes you are right, i have my desired setup in place. A 2 node mysql-cluster is in place, was just thinking about the possibility of sqlite db fs/block level replication. thank you everyone for putting thoughts on it. 

though my second question about track-calls performance went un-answered, i hope one of dev's can explain how it can degrade performance on a high load server.

keeping scalability in view i'd love to know how a rpc or curl backend for core db will perform :) though i know it's not yet implemented neither there are any chances but just a thought.

Regards,