Are there any best practices concerning what services should be cotenants on the same cluster nodes? From what I understand about Spark, it's basically designed to fully utilize the available memory and CPU on the host machine, within certain limits. Our usage of Spark has been very spiky so far--periods of inactivity followed by the entire cluster being pegged for short periods. In contrast, Hbase is designed to perform as a database, with fairly consistent performance, lower patency, etc. Would you recommend putting Hbase and Spark services on different nodes so the CPU spikes from Spark don't impact the Hbase service?