I recently synchronised an external hard disk which had approx 1.4 TB of data copied over with a GUI sync application on a Windows based file server. Sync direction, left to right.
The problem that occurred was the GUI application that did the sync was limited with the Windows Explorer 255 path size limit. As the data originated from a UNIX system, this prevent some folders/files from being copied, because they exceeded this limit.
I'm now wanting to use robocopy to pick up the remaining directories and files that were missed (because it doesn't have the path limitation), while not copying the whole lot again. Is there a combination of flags that I can use to achieve this?