As a tribute to being in Peter's country,
I'm offering a link to his blog for the first time in a while...you're
welcome for the traffic, Peter. :)
The occasion? Another example of Microsoft's insistent belief that Exchange's single instance store is a competitive advantage for Exchange. I'm not sure what article Peter is quoting in this blog entry, but he writes:
If a message is sent to one recipient and it is copied to 20 other recipients who reside in the same mailbox store, Exchange maintains only one copy of the message in its database. Pointers are then created. These pointers link both the original recipient and the 20 additional recipients to the original message.Yeah, been there, done that, have lots of t-shirts. It was called cc:Mail and it was a huge problem. Why? That shared store gets corrupted and bam! the whole post office was down. In Exchange 200X, they have this problem times 20 -- because Exchange actually doesn't have a single store anymore, they support up to 20. And oh, with no management tools to help an administrator decide which of the 20 storage groups to put a user's mailbox in. I can't see how MS can represent this as a competitive advantage with a straight face -- I even saw a customer presentation recently where they tried to cost justify a migration based on this one feature alone (!).
At any rate, Bill Buchan and Paul Mooney have the points right in their comments on Peter's site. Mr. Mooney writes "Disks are cheap - downtime isnt.". It's that simple. Domino's single mailbox per user architecture prevents a lot of service interruptions -- and when combined with the only viable active/active shared-nothing clustering, this is why so many Domino environments run 99.999%+ available. Simple.