What does a secondary namenode do in Hadoop?

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Hey. When I start all the daemons, I also see that there is a daemon called "Secondary Namenode". I wanted to know what is it used for because I cant find any operations to do on it. And does it start automatically?
Dec 20, 2018 in Big Data Hadoop by slayer
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The Secondary namenode is mainly used as a backup of namenode. The Secondary namenode collects checkpoints of metadata in namenode and then use it in case of namenode failure. 

We need not use Secondary namenode because standby namenode keep its state synchronized with the Active namenode.

When you use the ./start-all.sh command, it starts the Secondary namenode but you can choose not to start it by starting other daemons individually.

answered Dec 20, 2018 by Omkar
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