How to recover the decommissioning node's data. What actually happens with the data. Is it necessary to run hadoop balancer command, for start getting replicate the data into the other nodes for make the configured replication factor for each file.
When all the DataNodes report their state as Decommissioned (on the DataNodes page, or on the Decommissioned Nodes page at http://<NameNode_FQDN>:8088/cluster/ nodes/decommissioned), all of the blocks have been replicated. You can then shut down the decommissioned nodes.