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
#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 FutureQuest.net (work) Orlando, Florida kmk at sanitarium.net (personal) Web page: http://www.sanitarium.net/ PGP public key available on web site. ~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._., -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 224 bytes Desc: OpenPGP digital signature URL: <http://lists.samba.org/pipermail/rsync/attachments/20180116/41f060ec/signature.sig>
Thanks a lot, Kevin. I have a new Linux box and tried to set it to UTC but I think gnome outsmarted me... I'll use -rt and maybe ignore timestamps entirely rather than the window. If I find something wrong on the USB stick I can always copy it again. I love the -c option, but it takes forever on slow media. John On Tue, 2018-01-16 at 13:27 -0500, Kevin Korb via rsync wrote:> #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 > > > > > >