Using S3 storage with XRootD vs Dynafed

The High Energy Physics Research Computing group at UVic used Dynafed to create federated storage clusters for Belle II and ATLAS that were used by worker nodes deployed on cloud computing facilities around the world. Since the development on Dynafed stopped, XRootD was tested with S3 as backend to replace Dynafed. We will show the similarities as well as the major differences between the two systems for data transfers, checksum calculations as well as clustering of different endpoints, which may help others to efficiently make use of S3 storage as a WLCG site SE.