In issue #31970 I briefly mentioned that it would be awesome to directly backup/restore (migrate) vhosts via ssh - a brief search shows that this was also raised a few times on the forum, so this is just a summary of these discussions, along with the corresponding links:
http://virtualmin.com/node/25898#comment-115480 you could also explore using "rsync" for backing up one drive to another. Rsync is good at copying files, and only copying files that changed. Webmin/Virtualmin doesn't provide a front-end for that though, you'd have to build a script to handle that from the command line.
http://www.virtualmin.com/node/24681#comment-110857 Rsync isn't natively supported by Virtualmin, but that doesn't mean that you can't generate rsync backups on your own.
You could use Virtualmin to define a set of backups that don't include home directory data.
Then just use rsync to backup your home directory data.
http://www.virtualmin.com/node/7714#comment-31547 rsync would be a good option. Jamie just added incremental backups (still using tar, but with the Gnu tar incremental features enabled and handling of cleaning up old backup files), which we'll want to have in the field for a while before poking at again. ;-)
But, yes, I anticipate rsync will be added in the coming months. It's only problem is that it won't work to an S3 target, which is becoming one of our most popular backup destinations.
http://www.virtualmin.com/node/5016 I'm backing up all my Virtualmin domains nightly with a scheduled back, and i want to rsync them to another server after that has completed.
The need for a web-based rsync frontend was also discussed on WHT a while back, and it would seem like a useful extension to webmin's clustering support: http://www.webhostingtalk.com/showthread.php?t=1154078
Being able to easily manage rsync jobs across multiple machines would make webmin even more unique and useful to professional users.
Also, there have been quite a few discussions on automatically setting up "hot-spare" configurations via rsync, so this would be another reason why directly supporting rsync in webmin would be useful.