AWS EMR: do i need core nodes if I am planning to use EMRFS

Question

I am going through the online documentation and I found following diference between core not and task node.

1. Core node has hdfs while task node does not have HDFS.

due to above, AWS suggest it's not a good idea to scale core nodes based on load as hdfs re-balancing could take time and should re-balance task nodes only.

However, if I am planning to use EMRFS, do i need core nodes? what is the user of HDFS in this case if I am planning to access data from s3.

Answer 1

You need at least 1 Core Node.

If you want to use s3distcp after finish a job writing to local HDFS, then you need more such Core Nodes.