what happens if namenode is down - Wikitechy https://www.wikitechy.com/interview-questions/tag/what-happens-if-namenode-is-down/ Interview Questions Tue, 14 Sep 2021 09:36:20 +0000 en-US hourly 1 https://wordpress.org/?v=6.9 https://www.wikitechy.com/interview-questions/wp-content/uploads/2025/10/cropped-wikitechy-icon-32x32.png what happens if namenode is down - Wikitechy https://www.wikitechy.com/interview-questions/tag/what-happens-if-namenode-is-down/ 32 32 How to recover a NameNode when it is down ? https://www.wikitechy.com/interview-questions/big-data/how-to-recover-a-namenode-when-it-is-down/ https://www.wikitechy.com/interview-questions/big-data/how-to-recover-a-namenode-when-it-is-down/#respond Mon, 12 Jul 2021 17:44:14 +0000 https://www.wikitechy.com/interview-questions/?p=275

How to recover a NameNode when it is down ?

How to recover a NameNode
    • The following steps need to execute to make the Hadoop cluster up and running :
      • Use the FsImage which is file system metadata replica to start a new NameNode.
Name Node
    • Configure the DataNodes and also the clients to make them acknowledge the newly started NameNode.
    • Once the new NameNode completes loading the last checkpoint FsImage which has received enough block reports from the DataNodes, it will start to serve the client.
    • In case of large Hadoop clusters, the NameNode recovery process consumes a lot of time which turns out to be a more significant challenge in case of routine maintenance.
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