[Unison-hackers] Sneaker Net or Incremental Backup

[Duane McKinney]

I searched, but came up empty.  Can this be done.
I sync two offices using unison.  
1) (Optional)I would like to be able to set a preference that says, don't try to
sync a file if it would require X bytes transferred
2) Get a list of changed files from a root.  That way I can copy the files to a
removable drive and sync them when I get to the other office.

Here is my reasoning.  Most of the time, root changes are very small, a few MB.
 But Let's say that I download a new CENTOS release and place it on the file
server.  This may be a poor example, because I could retrieve it over the
internet again, but just bear with me.  I would like for unison, to instead of
trying to sync this file over the network to skip it.  The I would like to be
able to say once a week, run a job, that would take the differences in the root
and sent them to a USB drive.  I can then carry this drive to location 2, and
update the root there.   Then from my understanding, the network sync would
detect that both roots are identical.

That way, our bandwidth isn't being eaten up for hours/days, trying to perform a
sync that will most likely fail because it will take so long.

Also, this would be more useful, than synchronizing the whole root to a usb
drive, because, the total of the data that I am synchronizing is > 1TB.  I would
not mind moving a few GB (<100) via USB.  I am trying to avoid needing either, a
lot of time, or a bunch of USB drives (one for each root).

I have not yet looked at the source, but I would assume that most of the items
required for this feature are already in place.  Is it feasible?  Is there
already a way?