| Explain different modes in which Hadoop run
Below are the three different modes in which hadoop run
(1)Standalone Mode(Local):-By Default Hadoop use this mode and it is also called Local Mode. And we can also say that it runs in a local mode i.e. on a non-distributed, single mode. We use Hadoop in this Standlone Mode for mainly Learning, testing, and debugging. Hadoop works very much Fastest in this mode among 3 modes. To perform input and output operation we use local file system. As all of us knows HDFS is one of major components for Hadoop and this mode does not support the use of HDFS. Here we don't need to configure the below files:-
(i)hdfs-site.xml
(ii)mapred-site.xml
(iii)core-site.xml
for hadoop environment. Or we can also say that no custom configuration is needed for configuration files in this mode. All the processes in this mode will be run on a single JVM and this mode can only be used for small development purpose.
(2)Pseudo-Distributed Mode:-Like Standalone mode this mode will also runs on a single node. And in this mode every daemon (Namenode, Datanode, Secondary Name Node, Resource Manager and Node Manager) will run on separate process on separate JVM or in short we can say each daemon runs in separate Java process. As all daemons run on a single node and there is the same node for both the Master and Slave nodes. As these run on different java processes that is why it is called a Pseudo-distributed. Namenode and Resource Manager are used as Master and Datanode and Node Manager is used as a slave. A secondary name node is also used as a Master. The purpose of the Secondary Name node is to just keep the hourly based backup of the Name node. And this mode is used for development and for debugging purpose both. And HDFS is also used for managing the input and output processes. And we need to change configuration files given below :-
(i)mapred-site.xml
(ii)core-site.xml
(iii)hdfs-site.xml
for setting up the environment.
(3)Fully – Distributed Mode:-In this mode all the daemons run on separate individual nodes and thus forms a multi-node cluster. And in this node there are different nodes for master and slave nodes. This is the most important one in which multiple nodes are used few of them run the Master Daemon that are Namenode and Resource Manager and the rest of them run the Slave Daemon that are DataNode and Node Manager.Here Hadoop will run on the clusters of Machine or nodes. Here the data that is used is distributed across different nodes. | | |