The Metrics Collector is daemon that receives data from registered publishers (the Monitors and Sinks). The Collector itself is build using Hadoop technologies such as HBase Phoenix and ATS. The Collector can store data on the local filesystem (referred to as “embedded mode”) or use an external HDFS (referred to as “distributed mode”). It is a fully distributed collection and aggregation system starting from 2.7.0
Please refer to the wiki for more detailed info: https://cwiki.apache.org/confluence/display/AMBARI/Metrics