[Techtalk] backing up to vfat

Akkana Peck akkana at shallowsky.com
Mon Nov 30 18:11:15 UTC 2015

Miriam English writes:
> One of the problems is that for updating my backups I use
> cp -avu <source> <destination>
> On a linux-formatted drive this works nicely, not touching files that
> haven't been altered and only overwriting files that have changed.
> Unfortunately this isn't so with vfat-formatted drives, where it overwrites
> everything. This can end up taking a long time, which is really annoying if

I've never understood why the normal date comparison doesn't work
with vfat, since ls -l does show dates on vfat filesystems. I agree
it's annoying!

I didn't know cp had an option to not overwrite files that haven't
been changed. I use rsync, and when rsyncing to vfat filesytems or
filesystems mounted with curlftpfs, I use the --size-only flag:
  rsync -av --size-only <source> <destination>

It's not 100% reliable (especially with curlftpfs) but it works
pretty well with vfat. Of course it will miss changes that don't
affect the file size, but that's such a rare occurrence that I
don't worry about it.


More information about the Techtalk mailing list