Another important consideration in your Spark setup is security. If you are using Spark on EC2 with the default scripts, you will notice that access to your Spark cluster is restricted. This is a good idea even if you aren't running Spark inside EC2 since your Spark cluster will most likely have access to data you would rather not share with the world. (And even if it doesn't, you probably don't want to allow arbitrary code execution by strangers.) If your Spark cluster is already on a private network, that's great; otherwise, you should talk to your system's administrator about setting up some IPTables rules to restrict access.