Storage Groups for Exchange 2003

Some questions back to better clarify the answers you will recieve:

In your investigation of the environment, what is the average volume of mail recieved daily?

What regulations (SoX, HIPAA, etc) is the organization going to have to comply?

Front-End back end servers are based on workload with the general rule being 1 front-end for 4 back-ends, but this answer varies depending upon the client's uptime requirements and workload that will be placed upon them.

Exchange 24/7 would be an excellent book to pick up to assit with your planning.

Quest published a paper on Exchange Storage Best Practicies that you can pick up here:
http://wm.quest.com/reg/marketing/landing/exchangestoragemanagement/

Exchange server 2003 Enterprise edition supports maximum of 4 storage groups. Each storage group supports a maximum of 5 database. Hence 20 database can be supported on per server