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6. Decommissioning Masters and Slaves

Decommissioning is a process that supports removing a component from the cluster. You must decommission a master or slave running on a host before removing the component or host from service. Decommissioning helps prevent potential loss of data or service disruption. Decommissioning is available for the following component types:

  • DataNodes

  • NodeManagers

  • RegionServers

Decommissioning executes the following tasks:

  • For DataNodes, safely replicates the HDFS data to other DataNodes in the cluster.

  • For NodeManagers, stops accepting new job requests from the masters and stops the component.

  • For RegionServers, turns on drain mode and stops the component.