I use Subversion for source control, and it’s great. I recently migrated my repository to use the new FSFS backing store, which stores the repository directly on the filesystem, instead of in Berkeley DB.
One of the many advantages of FSFS is that it’s very easy to backup. The repository files can be copied directly. The only tricks are to copy the db/current file first, and not to copy the transactions/ directory. I backup my repository with rsync, like so:
rsync ... /path/to/repo/db/current backup:~/repo/db rsync ... --exclude transactions/ --exclude db/current \ /path/to/repo backup:~/