[Samba] samba as a file server

[moof48 at temple.edu]

I currently have samba 3.0.2 working with ldap as a filer 
sever Only.  My question is how would I get samba working as 
file server that would handle 50k users. My main concern is 
that I want reliability.  I would also like to be able to 
build horizantally if needed.  I was first thing some type 
of cluster connecting to a SAN but I would rather do it like 
we do our webservices.  We have x numer of small systems 
behind an alteon.  Could I do something like this with samba 
as just a file server.  Any recomendations on the setup?  

I also plan on looking into having samba doing some 
authentication for the different domains around our campus.  
Would you make our Samba file server a PDC  Excuse my 
limited knoweledge on all this domain and winblows stuff. I 
still have a lot more reading to do.