What are the modes in which Hadoop run?


What are the modes in which Hadoop run?

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?

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Re: What are the modes in which Hadoop run?

The modes in which you can run Hadoop::
These are:

1. Pseudo distributed Mode
2. Fully Distributed Mode
3. Standalone Mode


Execution Types

Pig has two EXECUTION TYPES or run modes, local and hadoop (currently called mapreduce)
1. Local mode
2. Map Reduce mode.

1) Local mode

 In Local mode, pig runs in a single JVM and accesses the local file system.
 This mode is suitable only for small data sets and typing out pig.
 To run in local mode, set the option to local i.e
%pig-x local


2) Map Reduce Mode

 In Map Reduce mode, pig translates queries into map reduce jobs and runs them on a hadoop cluster and cluster may be pseudo or fully distributed cluster.
 To use Map Reduce mode, we have to check the version of pig that is compatible with the versions of hadoop
 Pig honors the HADOOP-HOME environmental variable for finding which Hadoop client to run and pig will also use a bundled copy of the hadoop libraries.
 For pig, we have to set two properties in pig properties file which is pig’s cong directory.
i.e for psedudo distributed setup, example is

mapped. job. tracker=local host:8021
 Once you have configured pig to connect to Hadoop cluster, you can launch pig, setting the  -x option to map reduce or a map reduce mode is default i.e. % pig grunt>
Lucie Lina