HDFS High Availability

In this post we’ll see what is HDFS high availability, high availability architecture and the configuration needed for HDFS high availability in Hadoop cluster. Some background on HDFS high availability Prior to Hadoop 2, the NameNode was a single point of failure (SPOF) in an HDFS cluster. In a HDFS cluster there’s…

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Namenode in Safemode

This post shows what is Safemode in Namenode and what are the configurations for the safemode. You will also see the commands available to enter and leave the safemode explicitly. When the Namenode is started it loads the file system state into memory initially from the fsimage and then apply…

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What is HDFS Federation

This post shows what is HDFS federation in Hadoop framework and what configuration changes are required for setting up HDFS federation. Problem with HDFS architecture In a Hadoop cluster namespace management and block management both are done by Namenode. So, essentially the Namenode has to perform the following tasks- 1-…

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