This document discusses using Apache Cassandra to store and retrieve time series data more efficiently than the traditional RRDTool approach. It describes how Cassandra is well-suited for time series data due to its high write throughput, ability to store data sorted on disk, and partitioning and replication. The document also outlines a data model for storing time series metrics in Cassandra and discusses Newts, an open source time series data store built on Cassandra.