My coworker Colin McCabe and I recently gave a talk at Hadoop Summit Amsterdam titled “In-memory Caching in HDFS: Lower latency, same great taste.” I’m very pleased with how this feature turned out, since it was approximately a year-long effort going from initial design to production system. Combined with Impala, we showed up to a 6x performance improvement by running on cached data, and that number will only improve with time.
Slides: pptx
Video: Youtube