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. This eliminates the NameNode as a potential single point of failure (SPOF) in an HDFS cluster.
What does Hadoop do for High Availability?
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.
How many NameNodes can we have in a HA High Availability Hadoop architecture?
two NameNodes
HDFS HA Architecture: The HA architecture solved this problem of NameNode availability by allowing us to have two NameNodes in an active/passive configuration.
What is the role of NameNode in HDFS architecture?
The NameNode maintains the file system namespace. Any change to the file system namespace or its properties is recorded by the NameNode. An application can specify the number of replicas of a file that should be maintained by HDFS. The number of copies of a file is called the replication factor of that file.
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.
What is NameNode High Availability and how is it achieved in Hadoop 2?
Hadoop NameNode High Availability Architecture Hadoop 2.0 overcomes this SPOF by providing support for many NameNode. HDFS NameNode High Availability architecture provides the option of running two redundant NameNodes in the same cluster in an active/passive configuration with a hot standby.
What is the difference between a federation and high availability?
What jobs are optimized for scalability but not latency?
9. _______ jobs are optimized for scalability but not latency. Explanation: Hive Queries are translated to MapReduce jobs to exploit the scalability of MapReduce.
What is the job of the NameNode?
The NameNode is the centerpiece of an HDFS file system. It keeps the directory tree of all files in the file system, and tracks where across the cluster the file data is kept. It does not store the data of these files itself.
What is Hadoop NameNode?
NameNode is the master node in the Apache Hadoop HDFS Architecture that maintains and manages the blocks present on the DataNodes (slave nodes). NameNode is a very highly available server that manages the File System Namespace and controls access to files by clients.
What is NameNode Federation?
The namenodes are federated, that is, the namenodes are independent and don’t 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.
What happens if one NameNode goes down in Federation?
In HDFS federation, all the namenodes share a pool of metadata in which each namenode has it’s own pool hence providing fault-tolerance i.e if one namenode in a federation fails, it doesn’t affect the data of other namenodes. So, Federation = Multiple namenodes and no correlation.