Which node is responsible for high availability in Hadoop?

Which node is responsible for high availability in Hadoop?

NameNode
Hadoop 2.0 is keyed up to identify any failures in NameNode host and processes, so that it can automatically switch to the passive NameNode i.e. the Standby Node to ensure high availability of the HDFS services to the Big Data applications.

What is high availability in Hadoop?

The high availability feature in Hadoop ensures the availability of the Hadoop cluster without any downtime, even in unfavorable conditions like NameNode failure, DataNode failure, machine crash, etc. It means if the machine crashes, data will be accessible from another path.

What is the default replication factor in HDFS?

3
Each block has multiple copies in HDFS. A big file gets split into multiple blocks and each block gets stored to 3 different data nodes. The default replication factor is 3. Please note that no two copies will be on the same data node.

How would you configure a Hadoop cluster for high availability?

Setting Up and Configuring High Availability Cluster in Hadoop:

1. Extract the Hadoop tar ball.
2. Generate the SSH key in all the nodes.
3. In Active Namenode, copy the id_rsa.
4. Copy the NameNode public key to all the nodes using ssh-copy-id command.
5. Copy NameNode public key to data node.

What is the high availability feature in Hadoop?

A. Hadoop High Availability feature supports only single Namenode within a Hadoop cluster. B. Hadoop High Availability feature tackles the namenode failure problem for all the components in the hadoop stack. C. Hadoop High Availability feature tackles the namenode failure problem only for the MapReduce component in the hadoop stack.

How is HDFS distributed in a Hadoop cluster?

Hadoop HDFS High Availability – Introduction. Hadoop High Availability. HDFS is a distributed file system. It distributes data among the nodes in the cluster by creating a replica of the file. These replicas of files are stored on the other machines present in the HDFS cluster.

What are the issues with HDFS high availability?

There are two issues in maintaining the consistency of the HDFS high availability cluster. They are: The active node and the passive node should always be in sync with each other and must have the same metadata. This allows us to restore the Hadoop cluster to the same namespace where it crashed.

Which is the only node that knows the list of files in Hadoop?

NameNode is the only node that knows the list of files and directories in a Hadoop cluster. “The filesystem cannot be used without NameNode”. The addition of the High Availability feature in Hadoop 2 provides a fast failover to the Hadoop cluster.