Difference between single node pseudo-distributed mode in Hadoop

Question

I am new to Hadoop technology. I would like to know the basic difference between single node and pseudo distributed mode in hadoop.Will there be any difference from the configuration point of view?

Answer 1

Yes, there is a difference between the two at the configuration level.

Let's look at Standalone and Pseudo distributed mode one by one.

Single Node (Local Mode or Standalone Mode)
Standalone mode is the default mode in which Hadoop run. Standalone mode is mainly used for debugging where you don’t really use HDFS.
You can use input and output both as a local file system in standalone mode.

You also don’t need to do any custom configuration in the files- mapred-site.xml, core-site.xml, hdfs-site.xml.

Standalone mode is usually the fastest Hadoop modes as it uses the local file system for all the input and output.

Pseudo-distributed Mode
The pseudo-distributed mode is also known as a single-node cluster where both NameNode and DataNode will reside on the same machine.

In pseudo-distributed mode, all the Hadoop daemons will be running on a single node. Such configuration is mainly used while testing when we don’t need to think about the resources and other users sharing the resource.

In this architecture, a separate JVM is spawned for every Hadoop components as they could communicate across network sockets, effectively producing a fully functioning and optimized mini-cluster on a single host.

So, in case of this mode, changes in configuration files will be required for all the three files- mapred-site.xml, core-site.xml, hdfs-site.xml.

Hope this will clear the difference between the two modes.

Learn more about Big Data Architect and its concepts from the Big data architect certification.

Answer 2

In single node, a datanode and a tasktracker runs on the same system. And in pseudo-mode there can be mulitple datanode and tasktracker on the same system

Answer 3

Single mode runs a single process on one system and is not distributed. Pseudo-mode also runs on one system but it creates a cluster simulation

Answer 4

Single mode does not use hdfs, it used the local filesystem instead. But in pseudo-mode, hdfs is used. This how to storage and file system differs between these two modes.

Answer 5

Single mode doesnt run any daemons because it is non-distributed. The whole process is run on a JVM instance. But in case of pseudo mode, daemons are run on JVM instances.

Answer 6

Single node, as the name suggests run a single node on the system. Pseudo-distributed mode runs a distributed system but on the same system. So the cluster of nodes are created on the same system but you get to experience of a distributed mode.

Answer 7

Pseudo mode runs virtual nodes on the same system. In single mode, only one node is run and this mode is mainly used for debugging process.

Answer 8

Single node is used for debugging the logical part of the system and does nothing for the distributed file system because in this mode, local file system is used. In pseudo mode, distributed hdfs is used and allows developers to see how the system will behave in a fully distributed mode.

Answer 9

Understand it like this. Single node is a one-node system. Where there is only node on a same. There are no other nodes in the system and there are no other systems connected. It is just by itself. Pseudo mode is not connected to different system but it clusters number of virtual nodes on the same system.

Answer 10

Both are the same thing but single mode uses local file system and pseudo uses hdfs.