Fedora directory users - Nov 2008 - [ioggstream] peculiar deploy of fedorads

Hi all,

I''m planning a mid-size deploy of fedora-ds.
let''s call the units of this deploy "island"
islands are independent, data must be physically isolated betwen them

* an island represent a scalable, multi-mastered deploy of fedora-ds made of 
6+ nodes
* I have more islands: island1, island2, ..
* one island contains many  mailDomain (foo.it, foo.net, foo.com)
* a mailDomain is hosted on one island: if foo.it is on island1, it
won''t be
on island2
* each island has its own services accessing ldap

There''s one Rule-Them-All  (RTA) island with shared services.
Services on the "RTA" must access all ldap using the same search for
all the
island
ex. ldapsearch -h ruleThemAll  "(mail=foo@bar.com)" 
should find the user independently on which island it is.

question:
how will you implement this requirements trying to limit the overhead?
(somebody told me about a VirtualDS but I''d like to do it with FDS..)

Peace, R.