As another poster already pointed out, running two postmasters against the
same storage is officially a Very Bad Idea.
Also, it sounded like you might be looking at network attached storage
etc. to put your database on. While isn't a Very Bad Idea, it is a path
fraught with danger. For a database server, you're probably better off
having one very fast box that's either replicated or simply hot backed up
nightly from the live box. Any dual CPU machine with a gig of memory and
a stack of drives underneath it can handle two front end application
servers handily.
