What is MySQL Cluster's Practical Memory Limit?

We are designing a cloud SaaS, and are actively considering **MySQL Cluster** choice for our DB. We will be writing more than 100M rows/day to the DB. We need to understand if there is any practical memory limit. I understand that MySQL Cluster supports at max 48 data nodes, but is there practically any limit on the RAM each data node can have? RAM will be anyways expensive but we want to eliminate this if there is any hard limit. The question stems from this link: http://dev.mysql.com/doc/refman/5.6/en/mysql-cluster-ndb-innodb-engines.html , where Storage Limit is mentioned as **3TB**. It is slightly ambiguous to understand the way it is written. Thanks in advance.