Secondary Namenode: Connection refused

[#1]

am getting the below mentioned critical alerts in HDFS, please could you let me know whether secondary node process is mandatory for carrying out the activities or can it be ignored? if its mandatory let me know how to resolve this issue?

Connection failed to http://sandbox.hortonworks.com:50090 (<urlopen error [Errno 111] Connection refused>)

[#2 · Accepted solution]

Its not needed on a single node. In the latest sandbox, this process has been turned off (maintenance mode) to conserve resources.

On the sandbox page, see here for sandbox release notes for the current sandbox under section "Services not started automatically".

HDFS
SecondaryNameNode
*Since on a single node, secondary namenode is not needed, it is not started. 

For more details on what secondary name node does see here

If you are bored and have some time, this video also helps explain in way you won't soon forget 🙂