I'm looking at exchange licenses here: http://www.microsoft.com/exchange/2007/evaluation/editions.mspx
What do they mean by '5 storage groups' for the standard version and how do those relate to CALs?
I'm looking at exchange licenses here: http://www.microsoft.com/exchange/2007/evaluation/editions.mspx
What do they mean by '5 storage groups' for the standard version and how do those relate to CALs?
Storage groups are instances of the database engine used by Exchange. For mailbox servers with a need for very large scale, you can increase the overall IO throughput of Exchange by running multiple instances of the database engine (i.e. storage groups) and placing various mailbox databases and database transaction logs onto additional spindles or I/O subsystems, split up to balance the load and maximize throughput.
Additionally, since a database is the atomic unit of backup and restore in Exchange one might strategically balance mailbox load between databases to facilitate compliance with SLAs for various "tiers" of mailboxes.
Storage groups don't relate to CALs at all. This is a feature covered by the server license type, and not by the CAL type. The different types of CALs are used to license access to other features, as detailed in the table on that page you linked titled "Exchange 2007 CAL Offerings".