reHDFS documentation

reHDFS/README.md

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+# reHDFS (Reconfigurable Datacenter Network HDFS)
+
+reHDFS is modified HDFS block placement policy (i.e., it tells HDFS where to
+place replicas on write). reHDFS' policy is simple, given a writer on rack 1,
+place the replica in rack 2. Writers in rack 2 place replicas in rack 3,
+etc. When compared with the default policy (which chooses random racks), reHDFS
+creates a ring workload, as opposed to an all-to-all workload.