Guy Shilo explains erasure coding, a new feature in Hadoop 3:
The benefits are, of course, space-saving, and for large files also improved performance (blocks striped across datanodes can be read in parallel, and less blocks are written because there is no x3 replication). The larger the file the more notable is the performance gain.
Erasure encoding is disabled by default and you can enable it for only certain directories in HDFS. Some articles like this one suggest thatbest practice is to enable Erasure coding only for “cold” data that you do not write often, and for “hot” data use regular replication. However, in my tests I did not witness any problem dealing with hot data (maybe it’s evident in larger scales).
Click through for the full story on how it works.