I wanted to sync some directories on my machine to a shared folder on my server which runs Window Home Server. I used my backup s/w of choice, Cobian backup. A large percentage of files did not copy with errors like “The specified network name is no longer available” / “The network path was not found” / “The filename, directory name, or volume label syntax is incorrect”.
I also tried the free microsoft synctoy. It did not copy any additional files on the same sync with some of the same errors.
What worked for me in the end was surprisingly the free Microsoft, Robocopy. It has a default feature to skip files that already appear in the destination folder with identical size and timestamp.
robocopy source destination /e /zb /r:5 /purge
e.g. robocopy “f:\my documents\my music” \\myserver\music /e /zb /r:5 /purge
Update 14/Dec/12: Recently I removed a bunch of music from my hard drive as I was running out of space, so I have stopped using the /purge switch as this deletes destination files/dirs that no longer exist in source.