Tachyon by UC Berkeley AMP Lab.
From the webpage:
Tachyon is a fault tolerant distributed file system enabling reliable file sharing at memory-speed across cluster frameworks, such as Spark and MapReduce.It offers up to 300 times higher throughput than HDFS, by leveraging lineage information and using memory aggressively. Tachyon caches working set files in memory, and enables different jobs/queries and frameworks to access cached files at memory speed. Thus, Tachyon avoids going to disk to load datasets that is frequently read.
Since we aren’t quite to in-memory computing just yet, you may want to review Tachyon.
The numbers are very impressive.