Cassandra Deployement Architecture

i'm new on cassandra and i had the responsibility to design a basic deployement architecture for a use case, so i'd like to know if my solution is correct, and also have advices and recommendations from you.

here is the context : We need to create an application that will present some metrics[Scores, Number of visited pages..] to different kind of users[customers,admins..].

depending on the requests some metrics may required the last available data or not.

Actually we are using a third part software that stores RAW DATA into MySQL databases.

here is the solution that i think to deploy :

http://ift.tt/142Vesl

the "RealTime DataCenter" will be filled using either Cassandra Trigger or talend jobs.

thanks in advance