help a systems admin understand....

[William Ottley]

Hello all,
I have the daunting task of trying to understand what a programmer
needs as in hardware and implementation.
I have a general understanding of memcached, in that it speeds up the
"reads" from the database, since it goes into ram, and not go into the
database itself all the time.
What I'd like to know, is if we have several databases, and web
servers using memcached grabbing allocated memory and sharing this
memory across the servers, what happens to "writes"?

#1 can you have lets say 5 servers (2 web, and 3 databases) in 1
geographical location using memcached, and 5 other servers in another
geographical area connected via VPN using memcached, will this work?
#2 if web user A reads from a load balancer that sends him to a
database server in the US, and he writes something into the database,
HOW can a user B read this "written" data if the load balancer sends
him to a server located in China?

the reading I understand, its the writing that I'm having issues
understanding how on a global environment other users can
simultaneously see that write....

:$ hope I explained my question properly.

-- 
---------------
After this, there is no turning back. You take the blue pill - the
story ends, you wake up in your bed and believe whatever you want to
believe. You take the red pill - you stay in Wonderland and I show you
how deep the rabbit-hole goes.