Cumulus: Filesystem Backup to the Cloud

What is It?

Cumulus is a filesystem backup tool, somewhat similar to programs such as duplicity, Box Backup, and Brackup. Cumulus requires no special software at the server storing the backups—only the ability to store and retrieve entire files, making it well-suited for sending backups to services such as Amazon S3. An arbitrary number of backup snapshots may be created, or deleted at any point in time. Cumulus aims to optimize both storage and bandwidth costs; unchanged files (or even unchanged parts of files) are shared between snapshots. After the initial full backup, all backups are incrementals.

Cumulus was written by Michael Vrable.


Documentation is included with the source code (see below):

The Cumulus conference paper (FAST 2009) and Cumulus journal article (ACM TOS) contain more discussion of Cumulus, as does Michael Vrable's dissertation (in Chapter 3).


Warning: Cumulus is still under development, so do not yet trust it with critical data. Also, though functional, it is not yet very user friendly. However, the author has been using it for personal backups for several years.

The current release of cumulus is version 0.9:

Cumulus is released under the terms of the GNU GPL (version 2).

The current development version can be cloned using git from git:// or accessed via a web interface.