It is not a secret anymore! The Datawarehouse Hadoop cluster at Facebook has become the largest known Hadoop storage cluster in the world. Here are some of the details about this single HDFS cluster:21 PB of storage in a single HDFS cluster2000 machines12 TB per machine (a few machines have 24 TB each)1200 machines with 8 cores each + 800 machines with 16 cores each32 GB of RAM per machine15 map-r