What is high availability in NameNode?
The HDFS NameNode High Availability feature enables you to run redundant NameNodes in the same cluster in an Active/Passive configuration with a hot standby. In the case of an unplanned event such as a machine crash, the cluster would be unavailable until an operator restarted the NameNode.
How can we achieve high availability in Hadoop?
Setting Up and Configuring High Availability Cluster in Hadoop:
- Extract the Hadoop tar ball.
- Generate the SSH key in all the nodes.
- In Active Namenode, copy the id_rsa.
- Copy the NameNode public key to all the nodes using ssh-copy-id command.
- Copy NameNode public key to data node.
Which of the following is true about Hadoop High Availability?
2) Which of the following is true about Hadoop High Availability? i) Hadoop High Availability feature tackles the namenode failure problem only for the MapReduce component in the hadoop stack. ii) Hadoop High Availability feature supports only single Namenode within a Hadoop cluster.
Which architecture is used by HDFS?
NameNode and DataNodes HDFS has a master/slave architecture. An HDFS cluster consists of a single NameNode, a master server that manages the file system namespace and regulates access to files by clients.
What is the difference between a federation and high availability?
The main difference between HDFS High Availability and HDFS Federation would be that the namenodes in Federation aren’t related to each other. While in case of HDFS HA, there are two namenodes – Primary NN and Standby NN.
How does NameNode tackle DataNode failures and ensures high availability?
Using the metadata in its memory, name node identifies what all blocks are stored in this data node and identifies the other data nodes in which these blocks are stored. It also copies these blocks into some other data nodes to reestablish the replication factor. This is how, name node tackles data node failure.
How many nodes of Hadoop did you Yahoo test?
In 2007, Yahoo successfully tested Hadoop on a 1000 node cluster and start using it.
What is NameNode and DataNode in Hadoop architecture?
In Hadoop HDFS, NameNode is the master node and DataNodes are the slave nodes. The file in HDFS is stored as data blocks. The file is divided into blocks (A, B, C in the below GIF). These blocks get stored on different DataNodes based on the Rack Awareness Algorithm.
What is NameNode Federation in Hadoop?
The Namenodes are federated; the Namenodes are independent and do not require coordination with each other. The Datanodes are used as common storage for blocks by all the Namenodes. Each Datanode registers with all the Namenodes in the cluster. Datanodes send periodic heartbeats and block reports.
What is NFS gateway?
The NFS Gateway for HDFS allows clients to mount HDFS and interact with it through NFS, as if it were part of their local file system. The gateway supports NFSv3. After mounting HDFS, a user can: Browse the HDFS file system through their local file system on NFSv3 client-compatible operating systems.
How does HDFS HA work?
Hadoop HDFS provides High availability of data. When the client requests NameNode for data access, then the NameNode searches for all the nodes in which that data is available. After that, it provides access to that data to the user from the node in which data was quickly available.