Exchange 2010 Mailbox Database Size Expansion

RTmarc

Anyone have anedoctal experience with the size expansion of the databases from Exchange 2003/2007 to 2010? I can't seem to find any utilities that can estimate the size growth.

Claymoore

The mailbox role requirements calculator will tell you the DB size:
You Had Me At EHLO... : Exchange 2010 Mailbox Server Role Requirements Calculator

The calculator sizing formulas are based on the mailbox profiles you provide, specifically the quota and number and size of messages. The calculator will assume that everyone will max out their quota and only delete enough mail to continue to send and receive messages. This helps calculate the whitespace and dumpster sizes that add to the overall database size.

RTmarc

I'm looking for something that will examine my current database size and estimate the size after moving to Exchange 2010 which no longer supports single-instancing. I don't think that will do it for me.

Claymoore

If you are trying to determine the size of your DBs when you move to 2010, that calculator is exactly what you want. Any other tool would compound too many guesses to be of much use.

It's true that 2010 no longer has SIS, and that's a good thing. SIS reduced storage by approximately 20%, but at a cost to performance and scalability. 2010 loses SIS but adds compression of the message headers and body, but how much space that will save you is also a guess. If you are architecting your storage for Exchange, you don't just need to know what you need today but also what you will need for years to come. The storage calculator will tell you that.

it_consultant

From a purely experience based perspective, your databases will probably shrink unless you have been doing regular offline defrags of your 2003 information store. EDB files only grow, even when people delete things out of their inboxes. When you start with a nice fresh EDB file what was 75 GB may be much less.

I recommend that you clean inboxes first into PSTs, then import the old email directly into the Exchange 2010 archive (I assume you will use a separate archive datastore) to keep the whitespace in your active database to a minimum.

You lose the stream file as well once you move up to 2007 - 2010. All in all the more recent versions of Exchange are much more efficient when it comes to size and I/O.