For an Aster instance, Yet Another Resource Negotiator (YARN) is the resource management layer for the Apache Hadoop ecosystem that assists with the allocation of resources and the advancement of tasks.
Information on configuring YARN is documented in Set YARN Configuration Value Changes, and additional information about YARN (and asteryarn) is documented in the Teradata Aster® Execution Engine Aster Instance User Guide. This guide is available on the Teradata Information Products website: http://www.info.teradata.com.