I've got two FreeBSD machines set up; one serves video data and the other is the backup for the first. At this point I've got around 4TB of data. I add files to the video server a few at a time, and was planning to use rsync over ssh to keep the backup machine up to date.

I did the initial, large backup with both machines hooked up to the same subnet at the lab with no problems using rsync. Then, when I moved the backup machine off-site (but still on the university network), I attempted a sync without changing anything other than the IP (as the machine is now on a different subnet) and got the following error:

2010/03/22 15:55:21 [1260] rsync: connection unexpectedly closed (6340840244 bytes received so far) [receiver]
2010/03/22 15:55:21 [1260] rsync error: error in rsync protocol data stream (code 12) at io.c(601) [receiver=3.0.7]
2010/03/22 15:55:21 [1258] rsync: connection unexpectedly closed (60 bytes received so far) [generator]
2010/03/22 15:55:21 [1258] rsync error: unexplained error (code 255) at io.c(601) [generator=3.0.7]

The script that handles the backup hasn't been changed, nor has the crontab that invokes it. Does anyone have any ideas about what might be causing the hiccup? I was under the impression that it might have something to do with the ssh connection timing out or something along those lines, but am not entirely clear on how to diagnose the cause of the problem.