You can back up NFS cloud volumes by using Cloud Backup Service.
Cloud Backup Service expands the data protection capabilities of Cloud Volumes Service by delivering dedicated backups for long-term recovery, archive, and compliance. Backups created by the service are stored in AWS S3 object storage, independent of cloud volume snapshots that are available for near-term recovery or cloning.
Cloud Backup Service is currently in a beta release and supports only Cloud Volumes Service in the AWS US-WEST-2 region.
Before using Cloud Backup Service, you must understand and accept the terms, requirements, and considerations for using the beta software. See Setting Up Cloud Backup Service for NetApp Cloud Volumes Service for AWS for details and instructions about using the service.