We use a two-tiered backup solution for customer data. All files will be backed up on a daily basis and encrypted on the server using a PGP key and then uploaded to our secure cloud storage service. At the same time, they will also be uploaded to a separate cloud hosting service as a safety measure so that there is an up-to-date offsite backup as well. The communication between the two cloud hosts will be done via an encrypted connection (SSL) and sent as small 5MB chunks. Backups can be stored for lengthy periods of time as per your requirements.