top button
Flag Notify
    Connect to us
      Site Registration

Site Registration

Explain the difference between NameNode, Backup Node and Checkpoint NameNode?

+1 vote
386 views
Explain the difference between NameNode, Backup Node and Checkpoint NameNode?
posted Dec 22, 2016 by Karthick.c

Looking for an answer?  Promote on:
Facebook Share Button Twitter Share Button LinkedIn Share Button

Similar Questions
+6 votes
Backup NameNode metadata in HA configuration

We are using following version of Hadoop software: 2.0.0-cdh4.1.1. HDFS HA configuration is applied.

I would like to ask if there are any difference or possible side effects of backing up namenode data directory.

It is ok to just copy NN data directory from active NN to another host, what about standby NN? Or it may NN metadate can be in inconsistent state? Is there any advantages of using "hdfs dfsadmin -fetch " command?

+2 votes
Hadoop: namenode doesn't update block locations when data directories of a datanode is changed?

I am running hadoop-2.4.0 cluster. Each datanode has 10 disks, directories for 10 disks are specified in dfs.datanode.data.dir.

A few days ago, I modified dfs.datanode.data.dir of a datanode () to reduce disks. so two disks were excluded from dfs.datanode.data.dir, after the datanode was restarted, I expected that the namenode would update block locations. In other words, I thought the namenode should remove from block locations associated with blocks which were stored on excluded disks, but the namenode didnt update the block locations...

In my understanding, datanode send a block report to the namenode when datanode start so the namenode should update block locations immediately.

Is a bug? Could anyone please explain?

...