Is there a limit on file sizes that can be backed up?
There is no limitation on the file size at the application level. Instead this limitation is imposed by the underlying operating system.
The maximum theoretical file size on NTFS is 16 EB (16 × 10246 or 264 bytes) minus 1 kB or 18,446,744,073,709,550,592 bytes. With Windows 8 and Windows Server 2012, the maximum file size implemented is 256 TB minus 64 KB or 281,474,976,645,120 bytes.