Robert’s Rules of Exchange: Multi-Role Servers

@Matt Anderson - the definition of small, medium and large organizatoins is quite nebulous, isn't it?  I don't personally have a definition.  For the customers I deal with (Dept of Defense and other large government entities), anything less than 10,000 is a fairly small engagement.  Anything up to about 100,000 mailboxes is medium sized and the large ones are over 100,000 mailboxes.  But then, scale has to do with what you think, not some arbitrary number someone else gives you.

Bottom line in sizing Exchange is to use your hardware wisely.  Don't allocate more hardware than you need, but don't undersize your hardware.  Have twice the processor that you need is an expense that the current economy doesn't support.  Same with RAM.  And as for disks, you just don't need the performance or redundancy of a SAN any more because Exchange 2010 doesn't need the performance like older versions did, and the DAG provides the redundancy you need.  Why go for a Bugatti Veyron of disk subsystems?  Sure it can go 250mph, but why would you do that when the speed limit is 70mph max in most of the US?  What you need is a Ford Expedition Extended Length so that you can easily go the 70mph you need and take everything you own in the back!