Cumulus: Filesystem Backup to the Cloud.

In this paper we describe Cumulus, a system for efficiently implementing filesystem backups over the Internet. Cumulus is specifically designed under a thin cloud assumption--that the remote datacenter storing the backups does not provide any special backup services, but only provides a least-common-denominator storage interface (i.e., get and put of complete files). Cumulus aggregates data from small files for remote storage, and uses LFS-inspired segment cleaning to maintain storage efficiency. Cumulus also efficiently represents incremental changes, including edits to large files. While Cumulus can use virtually any storage service, we show that its efficiency is comparable to integrated approaches.