S3 and EMR data locality [closed]
EMR does not pull data from S3 to HDFS. It uses its own implementation of HDFS support on S3 (as if you are operating on an actual HDFS). https://docs.aws.amazon.com/emr/latest/ManagementGuide/emr-fs.html
As for data locality, S3 is RACK_LOCAL to EMR spark clusters.
As per the source mentioned below, EMR+S3 with EMRFS doesn't maintain data locality and is not suitable for analytics processing based on tools such as SQL. RedShift is the right choice for such use cases where compute and data are at one place. Please refer to 39:00 to 42:00 in the below link:
This is also mentioned in https://databricks.com/blog/2017/05/31/top-5-reasons-for-choosing-s3-over-hdfs.html. Please refer to the performance per dollar section.
To check how EMR works with S3 please refer to Programming elastic map reduce book by KEVIN SCHMIDT & CHRISTOPHER PHILLIPS(Chapter 1 Amazon Elastic MapReduce Versus Traditional Hadoop Installs section).