2-digit TB of graph data is for sure a serious graph :) Depending on what you actually want to analyze and how the graph is structured, you can either use our Pregel integration for high-level analytics of the data set or use SmartGraphs to shard the data to a cluster and perform in-depth traversals, pattern matching and such stuff. SmartGraphs is an Enterprise feature but free for evaluation and testing. Please note that the suitability of SmartGraphs depends on the structure of the graph itself (e.g. do you have or can identify communities to shard by efficiently)
We created a series of tutorials which guide you through such a process https://www.arangodb.com/pregel-community-detection/ (next step always at the end of each tutorial). You can choose between two storage engines. Think RocksDB is the better choice in your case, as everything is persisted to disk (data/indexes) and you can configure how much main memory should be used, so you can configure the trade-off between performance and main memory yourself. If you have fast SSDs it's even better, as RocksDB is optimized for that.