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I'm looking at exchange licenses here:

What do they mean by '5 storage groups' for the standard version and how do those relate to CALs?

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up vote 6 down vote accepted

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".

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1+ great answer. From what I have seen, 99% of Exchange deployments only use 1 storage group. – ITGuy24 Nov 2 '09 at 20:11
@ITGuy, yeah...but that's because most of the admins don't know the benefits of having multiple storage groups. To add to @Evan Anderson's post, it also reduces the time for maintenance and defrag. – Saif Khan Nov 2 '09 at 20:51
Also the old Exchange 2003 Standard Edition could only have one, so if they just migated to 2007 Admins may not be aware that 2007 can have up to 5 now. – SpaceManSpiff Nov 3 '09 at 0:14
Very well put. Thank you Evan. – SnOrfus Nov 4 '09 at 15:36

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