How should I be using rsync with FAT32/VFAT

Kevin Korb kmk at
Tue Jan 16 18:27:28 UTC 2018

#1 yes, you should use -rt instead of -a as everything else in -a is
incompatible with vfat.

#2 timestamps will always be a problem on vfat.  It has a 1 or 2 second
resolution so --modify-window=2 is a common solution.  However, if you
live somewhere that has yearly clock changes (we call it daylight
savings time) those will cause the timestamps to be off by an hour on
top of the 1-2 second problem.

The only potential solution I have ever found for #2 is to always run
rsync in a time zone that does not have clock changes (ie env TZ=UTC
rsync --modify-window=2 ....)  This way rsync will copy the timestamps
using the same interpretation of what they mean.

On 01/16/2018 12:48 PM, John Long via rsync wrote:
> Hi,
> I have been using rsync for over ten years. Thank you! It is a great
> tool.
> Recently I had the misfortune to have to use it to sync files to a USB
> stick that is for a platform that only supports FAT32.
> After missing the point a few times and having it copy some of the same
> directories and files needlessly I saw the timestamps on the source
> files (in reasonable filesystems like JFS, XFS, etc.) were a few
> seconds different from those on the VFAT filesystem on the USB check.
> Looking around the net this is a popular issue with FAT32 and people
> get around it by ignoring timestamps or by using -rt instead of the
> usual -a
> Do you have recommendations on the best way to keep file trees in sync
> when one of them is FAT32 and the other is a real filesystem?
> Thanks,
> John Long

	Kevin Korb			Phone:    (407) 252-6853
	Systems Administrator		Internet:
	FutureQuest, Inc.		Kevin at  (work)
	Orlando, Florida		kmk at (personal)
	Web page:
	PGP public key available on web site.

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