In this case, I would still recommend Cassandra. It can easily handler the data sizes you mention as well as the write rates you imply further down the thread.
Cassandra has a nice and simple architecture (every node is identical, no zookeeper roles etc), high write performance and scalability [1], and is fairly robust. My main piece of advice is to get the tables correctly set up. You need to know exactly what queries you want to make and design a table around that query (Cassandra only allows performant queries to be made, unless you go out of your way to set a flag). Whether a query is possible or performant depends on the key of the rows for the table, which may be a composite key. Take a look at the cassandra documentation for more details.
Cassandra has a nice and simple architecture (every node is identical, no zookeeper roles etc), high write performance and scalability [1], and is fairly robust. My main piece of advice is to get the tables correctly set up. You need to know exactly what queries you want to make and design a table around that query (Cassandra only allows performant queries to be made, unless you go out of your way to set a flag). Whether a query is possible or performant depends on the key of the rows for the table, which may be a composite key. Take a look at the cassandra documentation for more details.
1. http://techblog.netflix.com/2011/11/benchmarking-cassandra-s...