PostgreSQL on a Cluster

Hi,

I am trying to integrate an Enterprise level application to PostgreSQL.
I need answers to some questions:

This is what we are planning:

+---------------+
+ Storage +
+ Area +
+ Network +
+---------------+
+
+
-----------------
| |
Master Server 2nd Master
with eRServer Server
for load balancing
with eRServer

PostgreSQL can run only one server, right?

The PostgreSQL servers use SAN for storing data.

So let's say we want to do some operation on the database, located at SAN.
When the 1st server wants to update a row, it will lock it. What happens
when the second server wants to access the same row? Does 1st server
"broadcast" that it has locked the row?

Or... does MVCC have something with this?

How do we balance the load? Does eRServer do it; or should we use another
thing?

Maybe I need some documentation about these...

Thanks for reply.

Regards,

--
Devrim GUNDUZ
devrim(at)gunduz(dot)org devrim(dot)gunduz(at)linux(dot)org(dot)tr
http://www.gunduz.org