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rsync and FAT vs EXT file systems

NTFS/FAT timestamps can vary from those in EXT (Unix) systems like Mac OS. This causes issues when using rsync where every file is copied over even though nothing has really changed. Use the --modify-window=1 flag to tell rsync to allow larger time differences. In this case 1s.

So a typical incremental backup command will be

rsync -avz --modify-window=1 /src /dst
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