Session 4 (b) : Secondary Namenode & Checkpoint

Описание: Session 4 (b)

Now that we have covered fsimage and edits in the previous video we now discuss how fsimage is periodically updated to so that it has the latest filesystem state to avoid delays during Namenode restart. This process of periodic fsimage upgradation is called checkpoint. Also we will cover the role and significance of 'Secondary Namenode'

Topics covered:
The Checkpoint process
Edits log rotation
Role and significance of Secondary Namenode

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Commands used:

1) Entering safemode
hdfs dfsadmin -safemode enter

2) Leaving Safemode
hdfs dfsadmin -safemode enter

3) Update fsimage using SaveNamespace
hdfs dfsadmin -saveNamespace

4) Force secondaryNamenode to perform checkpoint
hdfs secondarynamenode -checkpoint force

5) Start secondary Namenode daemon
(hadoop_home)/sbin/hadoop-daemon.sh start secondarynamenode


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