rsync suddenly hanging indefinitely during transfers

Question

For the past few years, I have been using an rsync one-liner to back up important folders on my Mac Mini desktop (OSX 10.9, 2.5 GHz i5, 4 GB RAM) to a FreeNAS box (0.7.2 Sabanda

Answer 1

Most likely not "your" problem, but I stumbled upon this question when I was researching a similar behavior:

I'm observing "hanging" when the target site has too much io load. e.G. on one of my small business servers, when someone is resyncing his IMAP account and downloading large batchs of data and a backup job runs that writes his data.

In this situation I notice a steep drop in performance for rsync. Noticeable in a high load value in top on the target machine, even though CPU and Mem are fine.

Waiting for the process to finish has helped every time or interrupting and attempting the rsync at a later time again.