Does Hadoop use HBase as an "auxiliar" between the map and the reduce step?

Question

Or HBase does not have anything to do with this process?

I have read that Hbase works on top of hadoop, and I have seen some diagrams that shows Hbase as part of the MapReduce part of Hadoop, but I have not found anything concrete about my question.

Answer 1

The Map/Reduce framework itself doesn't rely on HBase. It would be interesting to see pointers to the diagrams you mention.

You can communicate with HBase in your map/reduce code, if you like (e.g. look up values by key).

HBase does work "on top of Hadoop": it stores its data in HDFS, relies on ZooKeeper, and its servers can run on the same cluster.