what does it mean "Client" in the HDP wizard installation about Hadoop components ?

[#1]

Hi all during HDP 2.5.3 installation, we are asked to "select" hadoop components topology.

where we would like to locate datanode (HDFS "slave") , nodemanager (for YARN) and so on ... no problem, perfect

the last one is "CLIENT". and HDP wizard mentions "CLIENT" means HDFS client, mapreduce client and so on ...

what is HDFS Client ? mapreduce client ? what does it mean from component and architecture point of view ? not equal to data node or task tracker ?

thanks

[#2 · Accepted solution]

Client means a set of binaries and libraries to run commands and develop software for a particular Hadoop service. So, if you install Hive client you can run beeline, if you install HBase client you can run HBase shell and so on. Typically you install all clients on so-called Edge (or Gateway) nodes, used by end-users to access cluster services. Some clients are also installed in the background (by Ambari) on master nodes for related services, like hdfs clients on NNs. Clients are passive components, unlike Data node, Node manager etc. they don't run unless someone starts related binaries.