I had similar situation and got nice quad cpu box and was killed by netbackup 
engineer with " breaking news" that NETBACKUP 4.5 IS NOT MULTI CPU AWARE 
application, it will NOT use more then one CPU during backups. May be veritas 
will fix that in V 5.0. so don't waste money, just get as much single cpu 
"horse power" as you can, tune up HBA's on host computers and you should be 
flying.
However, multi cpu can help if you would use storage/disk backup option in 
netbackup. 
Good luck!

> 
> From: "Fabbro, Andrew P" <Fabbro.Andrew AT cnf DOT com>
> Date: 2003/09/10 Wed PM 03:52:10 EDT
> To: "'jmaley AT macromedia DOT com'" <jmaley AT macromedia DOT com>, 
>    "Moses, Darby" <DMoses AT leviton DOT com>
> CC: Veritas-BU <veritas-bu AT mailman.eng.auburn DOT edu>
> Subject: [Veritas-bu] Driving LTO-2 Drives From Windows
> 
> We may have an environment where we'll be deploying LTO Gen-2 drives
> attached to a Windows media server.  The data will be coming in over 2Gbps
> SAN and I'm guessing 60MB/sec to write it out per drive (based on 30MB/sec
> we get with Gen-1).  We're 2GBps at all points so there shouldn't be any
> problems there...
> 
> ...but I'm wondering what size Windows box I'll need to drive 240MB/sec?  Is
> a 4-way enough?  8-way?  Anyone doing something like this?
> 
> --
>  Drew Fabbro [fabbro.andrew AT cnf DOT com]
>  Unix Systems Group
>  Desk: 503-450-3374
>  Cell: 503-701-0369
> _______________________________________________
> Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu
> http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu
>