Exchange 2007 - sizing

I’ve been collecting numbers!!

 

Maximum database size for Exchange 2007 is 16TB (Note: Maximum theoretical rather than maximum recommended. Recommended maximum is 100GB without CCR, 200GB with CCR). That is PER database so if you need to store more than 16TB of email on one server, you will need more than one database!

 

That wasn’t actually the reason for the sizing article though, this one is about RAM. A number of forums posts are highlighting hardware specifications without resorting to checking if these specs are appropriate.

 

Someone actually listed a server with Windows Enterprise and 32GB of RAM but seemed to have no idea about implementation. So I will pose the question – how can you spec up a server with 32GB of RAM without a rationale behind it?

 

Taking it as read that you know you need 2GB of RAM for the mailbox role, another 1GB for other roles, how much extra RAM do you need? Any?

 

The answer is yes – you need more RAM once you have users connecting. 2MB per light user, 3.5MB for a medium user and 5MB for a heavy user. Scale that up across your enterprise and even with 1,000 heavy users on a mailbox server means you only really need 7GB of RAM. However, there is another consideration – storage groups. It used to be the case that Exchange 2007 needed 0.5GB per storage group but this has now reduced.

 

Old calculation 0.5GB per storage group

New calculation 2GB plus storage groups/4 except for 1-4 storage groups where you only need 2GB.

 

So, when deciding how much RAM you need for Exchange 2007 with 48 storage groups on a dedicated mailbox server with 5,000 heavy users, you need:

 

Exchange requirement: 2GB

Storage groups requirement: 12GB

User requirement: 25GB

 

That makes 39GB of RAM so you’ll need Windows Enterprise Edition.

 

Since we came in with the 16TB per database, what can we do with that? 48 storage groups, each containing 1 database of 16TB means 768TB of emails on that server. That’s a *lot* of spindles and we haven’t even thought about the IO requirements and therefore the number of spindles required.

 

Ordering a server and a set of RAID arrays to match that box will make someone’s year – maybe there is a small child somewhere who received a very big Christmas present from a father who received just such an order.

 

If that’s you, do you need any odd jobs doing?