What are the modes in which Hadoop run?

[DataFlair Team]

What are Different modes of Hadoop?
What is the difference between Standalone Mode & pseudo-distributed mode in Hadoop?
What are the modes Hadoop can run in?

[DataFlair Team]

What are Different modes of Hadoop?

• Standalone Mode
• Pseudo Distributed Mode(Single-Node Cluster)
• Fully distributed mode (or multiple node cluster)

What is the difference between Standalone Mode & pseudo-distributed mode in Hadoop?

1) Standalone Mode:

• No Custom Configuration is required in 3 hadoop(mapred-site.xml,core-site.xml, hdfs-site.xml) files.
• Used for debugging purpose
• Standalone mode is much faster than the Pseudo-distributed mode.
• Local file system is used for input and output
• HDFS is not utilized in this mode

2) Pseudo Distributed Mode (Single-Node Cluster):

• Configuration is required in given 3 files for this mode
• Used for Real Code to test in HDFS.
• Pseudo-distributed cluster is a cluster where all daemons are
running on one node itself.
• Here one node will be used as Master Node / Data Node / Job Tracker / Task Tracker
• Replication factory is one for HDFS

What are the modes Hadoop can run in?

We can run a Hadoop in one of the 3 supported modes as below

1) Standalone Mode

By default, Hadoop is configured to run in a Standalone Mode, non-distributed mode, as a single Java process. This is useful for debugging. This does not offer you a true distributed environment. The usage of this mode is very limited and it can be only used for experimentation.

2) Pseudo-Distributed Mode

Hadoop is run on a single node in a pseudo(false) distributed mode, Just like the Standalone mode. The difference is that each Hadoop daemon runs in a separate Java process in Pseudo-Distributed Mode. Whereas in Local mode each Hadoop daemon runs as a single Java process. Again the usage of this mode is very limited and it can be only used for experimentation.

3) Fully-Distributed Mode

In the fully-distributed mode, all daemons are executed in separate nodes forming a multi-node cluster. This setup offers true distributed computing capability and offers built-in reliability, scalability and Fault Tolerance.

[DataFlair Team]

Hadoop can run in following modes.
Standalone Mode
1. Default mode for Hadoop
2. HDFS is not utilized here instead local file system is used for input and output.
3. Mainly used for debugging purpose.
4. Custom configuration not required within 3 Hadoop files(mapred-site.xml, core-site.xml,hdfs-site.xml)
5. Faster that Pseudo-distributed node.

Pseudo-distributed mode
1. This is the cluster where all Daemons(Master Node, Data Node, Resource Manager, Node Manager) runs on one node.
2. Replication factor is 1 for HDFS.
3. Custom configuration required within 3 Hadoop files(mapred-site.xml, core-site.xml,hdfs-site.xml)

Fully-Distributed mode
1. This is mainly used in Production phase.
2. Data is stored and processed accross multiple nodes.
3. Different node will be used as all Daemons(Master Node, Data Node, Resource Manager, Node Manager)

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