Management is deciding if it would be smart to consolidate all exchange servers in site to a clustered Super Server. Should we?? There will be a Compaq SAN solution implemented for fault tolerance

Exisiting:

6 Priv/Pub servers running almost 400GB IS total. Most hardware a few years and should be upgrade to new servers

Question: Should we upgrade to one massive computer (clustered) to consolidate everything. Or should we buy 4 smaller computers not clustered to spread the load across and eliminate a single point of failure?

My thoughts... Maintenance (Defrag: How long to defrag 400GB IS?) Recovery (How long to restore 400GB IS?) Solution for Recovery: Superdat ADIC connected to server that backs up 260GB/Hr.

Manager suggested doing nightly defragging for maintenance. Is this smart? What would be the upsides and downsides?

Thanks for any input you may have. This is a major decision for us obviously and unfortunately I don't have the "pull" to make the decision, only recommend something. I recommended the later, but mgmt is pushing 1 Super Server.