Most migration cases can be handled by a great tool we wrote called ecs-sync, found here.
An HDFS migration is possible with s3distcp or distcp. Please note that
if using s3distcp with the s3a driver, it needs to be the latest version
or you may run into issues. If using distcp, ECS’s HCFS driver “viprfs”
will need to be set up as a secondary FS and the distcp made from
hdfs://... to viprfs://.... Instructions for installing the HCFS
driver can be found
here.