rsync: A Backup Strategy for Modern Times - Page 4
Running an rsync Server
rsync can also be run as a daemon, which can be invoked from the command line --daemon. rsync listens on TCP port 873. Setting up a dedicated rsync server lets any number of machines and users connect for mirroring, backups, file retrieval, whatever they need. /etc/rsyncd.conf contains the server's environment and runtime variables, including user and host access control lists.
The best and safest way to use rsync is to run it from scripts. Refine your command strings and directory options, then record them for posterity in scripts. Put them in crontabs so you don't have to remember to run them manually. Using (and reusing) scripts greatly reduces the chances of errors. See the rsync web site for examples of backup scripts. The site gives examples for using an ordinary 7-day rotation to a central backup server, mirroring a CVS tree, and backing up to a spare disk.