How do you handle the failure of Data node

0 votes

When we write a file in Hadoop and if there is any failure happens to Data node how its going to get handled?

Apr 9, 2019 in Big Data Hadoop by anonymous
543 views

1 answer to this question.

0 votes

HDFS has Master Slave architecture in which Master is Namenode and slave is Datanode. 

HDFS cluster has single namenode that manages file system namespace (metadata) and multiple datanodes that are responsible for storing actual data in HDFS and performing read-write operation.

In HDFS, Each Datanode in the cluster sends a heartbeat in an interval of specified time to the Namenode. If it receives any heartbeat that means the Datanodes are working properly. 

If the Namenode doesn’t receive the heartbeat signal, it assumes that either Datanode is dead or non-functioning properly. As soon as the datanodes are declared dead. Data blocks on the failed Datanode are replicated on other Datanodes based on the specified replication factor in hdfs-site.xml file. 

Once the failed datanodes comes back the Name node will manage the replication factor again. This is how Namenode handles the failure of data node. 

answered Apr 9, 2019 by Gitika
• 65,870 points

edited Apr 9, 2019 by Gitika

Related Questions In Big Data Hadoop

0 votes
2 answers

How do I output the results of a HiveQL query to CSV?

Hi, The insert overwrite directory is running in ...READ MORE

answered Dec 18, 2020 in Big Data Hadoop by akhtar
• 38,180 points
154 views
0 votes
1 answer

What do we exactly mean by “Hadoop” – the definition of Hadoop?

The official definition of Apache Hadoop given ...READ MORE

answered Mar 16, 2018 in Big Data Hadoop by Shubham
986 views
0 votes
1 answer

How do I include all the Hadoop dependencies using Maven?

This is a dependency mismatch error. I ...READ MORE

answered Apr 10, 2018 in Big Data Hadoop by Shubham
• 13,480 points
3,321 views
0 votes
1 answer

How to set the number of Map & Reduce tasks?

The map tasks created for a job ...READ MORE

answered Apr 18, 2018 in Big Data Hadoop by Shubham
• 13,480 points
340 views
0 votes
1 answer

How to print the content of a file in console present in HDFS?

Yes, you can use hdfs dfs command ...READ MORE

answered Apr 19, 2018 in Big Data Hadoop by Shubham
• 13,480 points
2,830 views
0 votes
1 answer

How to extract only few lines of data from HDFS?

Here also in case of Hadoop, it is ...READ MORE

answered May 2, 2018 in Big Data Hadoop by nitinrawat895
• 11,380 points
5,104 views
0 votes
1 answer
0 votes
1 answer

How can you Check the xml definition of a Workflow, Coordinator or Bundle Job in Oozie?

Hey, You can use this example so that ...READ MORE

answered Jun 24, 2019 in Big Data Hadoop by Gitika
• 65,870 points
171 views