I have a 1TB external drive that syncs nicely between two windows machines, however, I have a similar issue with sync crashing on ARM (a raspberry pi) and two possible causes. The permissions are not set to allow sync to write to the folder(s) The index file that sync creates is too bulky for the pi to process with its limited memory and it falls over when syncing large directoriesFor information, I wouldn't recommend using sync to do the initial file transfer. Use rsync on linux, robocopy or FreeFileSync on Windows. My guess is that the crash in my case is a result of poor permissions.
