Major Description
HDFS has added Erasure Coding support in HDFS-7285. There are HDFS level ReadStatistics so from DFSClient we can know how much reads are EC/replication.
In order for users to have a better view of how much of their workload is impacted by EC, we can expose EC read bytes to File System Counters, and to MapReduce's job counters. This way, end users can tell from MR jobs directly.
