Synchronising two (identical) databases

Hi all,
The group I'm in, have a small dilemma. we would like to have two
databases (identical) at diff locations which are sync and entries being
add into each at the same times.

The set up at the moment:
Have a local copy (DB1) which most of the work is done through. About
once a month we run a large job which adds ~2mill entries into various
tables. Which we run on our local linux cluster and other local
machines. Kool.

However, we would like to run more then one job at a time. We now have
access to an other linux cluster which is behind a fire wall (the admin.
is out of our hands :( ) and we are unable to remotely connect to DB1
through the each separate node. A possible work around is to pass all
queries through the main head node which can connect to DB1. This has
obvious performance restrictions.

So we would like to have an identical copy of DB1 on this cluster
(database DB2). For all the tables we're using ints as primary key types
and using the sequence tables to generate the key. Is there away to sync
the two databases in such a situation. Can someone can point me in the
right direction, it would be much appreciated.

Another idea we had was to place the ip address (or something sim) of
each cluster at the start of the ids (ensuring uniqueness). But is it
possible to change the field type of a column without dropping the table
and recreating it??

Yes I would like to run two or more jobs at the same time.

Many thanks
--

Noel Faux
Department of Biochemistry and Molecular Biology
Monash University
Clayton 3168
Victoria
Australia