mogilefs and geographic redundancy

[Jeff Lewis]

MogileFs appears to be precisely the system I am looking for for data
archival.  But I do have a question:

We basically have 2 datacenters that are in different locations.  Each
is supposed to be an exact copy of the other at any given time - within
reason.  I can see running MogileFS in each of the 2 locations, but how
then, do I keep them in sync?

Q:  Does anyone have an suggestions on how to keep these 2 sites in
sync?

Here is 1 possible idea that I had:  Right now, a class knows how many
instances of a given file should be kept around and mogilefs know which
servers it has available for use.  What if a class could know about
blocks of servers to use.  Each block could then have a replication
count for that class.  That way at the main data center, say I want 4
copies of a particular class of file, but at the secondary data center,
maybe 2 copies would be sufficient.

Any ideas or obvious solutions that I am missing?  Thanks,