In this recipe, we will be configuring Secondary Namenode, which is a checkpointing node. In the very first recipe of this chapter, we say that it is critical to manage metadata and keep it clean as often as possible.
The Secondary Namenode can have multiple roles such as backup node, checkpointing node, and so on. The most common is the checkpointing node, which pulls the metadata from Namenode and also does merging of the fsimage and edits logs, which is called the check pointing process and pushes the rolled copy back to the Primary Namenode.
Make sure that the user has a running cluster with HDFS and has one more node to be used as Secondary. The master2 node, from the Namenode HA using shared storage recipe in Chapter 4, High Availability can be used as a Secondary Namenode or Secondary Namenode can co-exist with the Primary Namenode.
When running Namenode HA, there is no need to run Secondary Namenode, as the standby Namenode will do the job...