Namenode v s Secondary namenode

+1 vote
Hadoop is Consistent and partition tolerant, i.e. It falls under the CP category of the CAP theoram.

Hadoop is not available because all the nodes are dependent on the name node. If the name node falls the cluster goes down.

But considering the fact that the HDFS cluster has a secondary name node why cant we call hadoop as available. If the name node is down the secondary name node can be used for the writes.

What is the major difference between name node and secondary name node that makes hadoop unavailable.

Thanks in advance.
Sep 9, 2019 in Big Data Hadoop by nitinrawat895
• 11,380 points
491 views

1 answer to this question.

+1 vote
Name Node is a primary node in which all the metadata is stored into fsimage and edit log files periodically. But, when name node down secondary node will be online but this node only has the read access to the fsimage and edit log files and don't have the write access to them. All the secondary node operations will be stored to the temp folder. when name node back to online this temp folder will be copied to name node and the namenode will update the fsimage and edit log files.
answered Sep 9, 2019 by ravikiran
• 4,620 points
Good Answer Ravikiran..Also could you please let us know what is the temp folder name which the fs image and editlogs of secondary namenode will save .SPOF is overcomed by High availability is that accurate?

The name of the directory where you will find fs image and editlogs will be in the directory mentioned to the dfs.name.dir option in the hdfs-site.xml file. 

Yes, SPOF can be solved by High Availability. You can read more on High Availability here: https://www.edureka.co/blog/how-to-set-up-hadoop-cluster-with-hdfs-high-availability/ 

Related Questions In Big Data Hadoop

0 votes
3 answers

What are differences between NameNode and Secondary NameNode?

File metadata information is stored by Namenode ...READ MORE

answered Apr 7, 2019 in Big Data Hadoop by anonymous
6,700 views
0 votes
1 answer

How to configure secondary namenode in Hadoop 2.x ?

bin/hadoop-daemon.sh start [namenode | secondarynamenode | datanode ...READ MORE

answered Apr 6, 2018 in Big Data Hadoop by kurt_cobain
• 9,390 points
943 views
0 votes
1 answer

What does a secondary namenode do in Hadoop?

The Secondary namenode is mainly used as a ...READ MORE

answered Dec 20, 2018 in Big Data Hadoop by Omkar
• 69,130 points
408 views
0 votes
2 answers

How to set properties for secondary namenode in Hadoop?

Secondary NameNode in HDFS Secondary NameNode in Hadoop ...READ MORE

answered Mar 31, 2020 in Big Data Hadoop by anonymous
722 views
+1 vote
1 answer

Hadoop Mapreduce word count Program

Firstly you need to understand the concept ...READ MORE

answered Mar 16, 2018 in Data Analytics by nitinrawat895
• 11,380 points
7,202 views
0 votes
1 answer

hadoop.mapred vs hadoop.mapreduce?

org.apache.hadoop.mapred is the Old API  org.apache.hadoop.mapreduce is the ...READ MORE

answered Mar 16, 2018 in Data Analytics by nitinrawat895
• 11,380 points
1,168 views
+2 votes
11 answers

hadoop fs -put command?

Hi, You can create one directory in HDFS ...READ MORE

answered Mar 16, 2018 in Big Data Hadoop by nitinrawat895
• 11,380 points
52,747 views
–1 vote
1 answer

Hadoop dfs -ls command?

In your case there is no difference ...READ MORE

answered Mar 16, 2018 in Big Data Hadoop by kurt_cobain
• 9,390 points
2,725 views
0 votes
1 answer

Differences between Cassandra and Hadoop, Real-time Processing v/s Batch Processing

Hadoop is basically designed including HDFS loaded with ...READ MORE

answered Jun 18, 2019 in Big Data Hadoop by ravikiran
• 4,620 points
154 views
0 votes
1 answer

Explain to me the difference between name node and secondary name node.

Firstly, You need to understand the major ...READ MORE

answered Apr 30, 2019 in Big Data Hadoop by ravikiran
• 4,620 points
274 views