How to Safely Decommission HBase Region Servers and HDFS Data Nodes

[#1]

If we are going to decomm a data node on which a region server is also running :

1. first - is that a viable option? Can a data node be decommissioned when a region server is also running on that host? Doesn't the region server have/use data on that data node - if so, then how can the data node be decommissioned?

2. let us suppose to due some severed hardware error the node has to be decommed. Then is it necessary to shift the region server on to another node? Or (if there is no real issue with the hardware etc) can a region server exist on a machine without a data node on it?

3. Is there anything to be done to HBASE/Region Server (maintenance mode etc) when you decommission a data node?

Appreciate the insights.

[#2 · Accepted solution]

1. Yes, you have to go to host and decommission RS first, it will put HBase RS into drain mode, then you can continue with decommissioning DN.

2. RS can live without DN but due to data locality it is best to coexist

3.see #1

https://docs.hortonworks.com/HDPDocuments/HDP2/HDP-2.5.3/bk_administration/content/ch_slave_nodes.ht...

[#3]

can we directly Decommission the HBase region server after adding the new region server to the HBase?will there be any data loss? 

[#4]

@KPG1 

As this is an older post we recommend starting a new thread. This will provide the opportunity to provide details specific to your environment that could aid others in providing a more accurate answer to your question.