Here's my situation. Two Exchange servers both have about 250GB for Mail Stores (500GB total). I have 90 mailboxes totaling approx. 233GB. I need to load balance these 90 users across the two servers. What's better? One Storage Group with one mail store on each server where the mail store will be approx. 116GB in size or setup multiple mail stores and have maybe 25 to 30GBs per mail store? I think this comes down to a question of single instance storage and what can be gained by using it. If I stick to one big mail store I should get better single instance storage. But maybe I'll have poorer performance since more users will be trying to hit the same edb. Any thoughts? Thanks

So as I'm starting to think this through I'm leaning toward more smaller mail stores then one big one. I guess I like the idea of being able to affect less users if a mail store needs to be brought offline more then what might be gained by single instance storage. Your feedback welcome....

All depends of your backup/restore time requirements in SLA.The best practice is to have SOME small databases than ONE big.

exchange 2007 encourages a 1:1 ratio with storage groups to stores. they want you to have more, so you have greater backup flexibility. I'd maybe make several stores with no more than 75GB per.