so now the question I have is how do I set up the drives?For example: Currently I have four sets of 90 gig SAN disks with one storage group that contains 3-4 DB's. I know I have to have one SG per DBto do CCRbut how does that affect the drives? Can I keep the current setup with 3-4 DBs on the 90 gig? Or should I break that into smaller disks and put one SG/DB?

No need to break in to smaller disk....IF you want you can make single RAID for four sets of 90 gig SAN disks and spilt in to disk partion as per you DB size...But be sure the partion size ,name should be identical for both the nodes....

Always go for SG/DB. Below article will give you clear idea of requirements http://www.telnetport25.com/component/content/article/16-exchange-2007-ccr/298-exchange-2007-ccr-going-pro-as-in-production-part-1-some-food-for-thought-or-perhaps-not.html Vinod |CCNA|MCSE 2003 +Messaging|MCTS|ITIL V3|

Try Vinod post

Splitting disks and putting one SG/DB in different drives gives better performance when you have multiple LUNs of RAID-10 but splitting one RAID-10 LUN into different partitions to put one SG/DB in each won't give you any performancebenefit. So if you don't have different LUNs then put all of them on single LUN and if possible put transaction logs and otherprotocol & trackinglogs on different LUN <or on OS LUN for getter performance>...Amit Tank | MVP Exchange Server | MCITP: EMA | MCSA: M | http://ExchangeShare.WordPress.com

Yes Amit sugesstion looks better and it will be come under best practice