I am sorry if this has been brought up before. I tried a search, I think I need to use rsync, but was unable to find what I needed. I have a Unraid system that I currently have all my data on. I am building one for my sister, when it is done it will be moved to a different state. What I am looking for is a way to keep one or two shares in sync with both servers. So what I am thinking is after building her server copying over the user share "Pictures" and "Family Videos" and then shipping it off to her. Then every month (or what ever interval I need) plugging in a external drive (either hard drive or thumb drive) into my server would copy all data that has been added since last sync, I then mail it to her, she plugs it in and it copies all data to her server, then replaces it with the new data on hers and she mails it back to me completing the loop. If it is easier the data from her server doesn't need to be added, mine is the main server that will get new information. Is this possible?

Had a similar question previously.  Here's the link to the thread:

http://lime-technology.com/forum/index.php?topic=11341.msg107842#msg107842