Complicated mixed exchange environment, looking to move to 2010!

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Roy DuqueDDE

Ok here is the deal. In my company we have what i think to be a complicated exchange environment.

There are 2 domains, Domain A-Alpha(the old domain) and Domain B-Bravo(the new domain).
Email domain name:

Our company has forced us to migrate users to Bravo and keep exchange running at the same time. Now these domains are in different forest and there is a 2-way transitive trust between the forest.

Alpha has 2 exchange servers.

Alpha1- is the bridgehead exchange enterprise 2003 sp2 server. This server is the original exchange server of the company and has the remaining mailboxes on it. All mailflow goes through this server.

Alpha2- is a secondary exchange 2003 server i installed which just has mailboxes on it(this was installed for performance reasons).

Also there is a brightmail server which is on our DMZ which is where our MX records point to. All email in/out of our company goes through this server. Alpha1 is configured to route external mail through this brightmail server by using it as a "smarthost" in the exchange configuration.

Bravo domain currently has 2 servers.
Bravo1 - Exchange 2007 enterprise sp1 which i installed in order to get mailflow between the 2 domains working. After working with microsoft i was able to get smtp name sharing working across both the domains so that all mail went in/out the Alpha1 exchange server.

Bravo2 - Exchange 2010 server which i installed all the roles on (except for the UM role). There are no mailboxes on this server as of yet as i plant to migrate everyone/everything to this server.

Couple of things to note:
A. There is smtp name sharing configured between the 2 domains(we wanted to keep the same name between the 2 exchange servers in different organizations).
B. Exchange 2010 has already been installed in Bravo domain with all the roles on a single server(Bravo2). So all the AD and exchange pre-reqs on the bravo domain have already been installed
C. There are public folders replicating between the Alpha and Bravo exchange servers
D. We have about 900 mailboxes in total and our executives use iphones to check email.
E. We have a blackberry server on the alpha domain which we also have to migrate.

Here are my issues.

1. What are the best practices as far as "roles" in an exchange 2010 environment.
Should the mailbox role be a physical server with local storage?
Can the cas server be a VM? if so how many cas servers would we need? Would having CAS on a VM affect user front-end performance?
Can i separate the 2010 roles after I have already installed them all on Bravo2?
I would like to setup at least one DAG for redundancy after everything has been migrated, or can this be done prior to the migration?
2. What are the steps I need in order to get everyone on the 2010 environment and get rid of the name sharing between the forest and connect Bravo2 directly to our brightmail box on the dmz. We also want to get rid of the exchange 2007 server(bravo1).

3. Many of our executives have 8+gb mailboxes and are complaining of performance hits in outlook when tryign to browse email on alpha1 server. Will this still be an issue with 2010? we do not have any archiving solution in place(yet) so they need to keep all these emails.

4. There is a captaris rightfax connector on the alpha1 server that also needs to be migrated to 2010.

All the executive/corporate mailboxes are still on the Alpha1 server. This is mainly because we havent migrated there pc's to the new bravo domain, and because they are using blackberrys which our bes server is on the alpha domain so i cant move them over until i setup a temporary bes server on the new domain.

All the other mailboxes for the company have already been migrated to the Bravo1 server on the new domain(regular staff).

I apologize for the long explanation but I felt it was necessary. And i may have even left some stuff out.

Thank you in advance to anyone who can help me out with this as it seems like a huge project.


no so complicated, have seen worst :D

well, let us asnwer each question one by one:

1- this is based on the Exchange design you want to do, local storage is OK if you don't want to invest in storage and dont have a SAN, SAN provides more storage and more scalable architecture.

what you should take care about is storage size, performance and if local storage is ok then go with it, I can see that you have a SAN to better to use it.

for the CAS server you start by sizing the mailbox servers, and how many core are needed for the MBX, then take that and make it with the ratio 4:3 core and then you will know how many core you need and how many server you need.

the CAS can be a VM but the VM must be the same HW config that you need for the physcial one.

yes you can separate them later.

DAG setup can be done after the migration.

2- move all of the users to the 2010 server and then de-comission the 2007 servers in old and new forest.

3- 2010 should run faster, and can handle up to 10 GB mailbox.

Regards, Mahmoud Magdy Watch Arabic Level 300 Videos about Exchange 2010 here: Read pretty advanced Exchange stuff I post here:, follow my blog: , corp blog: and if you Liked my post please mark it as helpful and accept it as an answer

Roy DuqueDDE

when you say how many "core" are needed. you mean cpu cores?
For 2010, i think i read that it does not work the same as 2007, i do not need to seperate the log files and database files on different luns or drives for better performance. is this correct?

I do not have any exchange 2007 in the old forest, only the new forest.

I have 1 user with a 14gb mailbox in the alpha1 exchange server, will this be an issue when i migrate her over to 2010?

should i just move all the mailboxes from the bravo1 server to bravo2? will the outlook clients know to redirect themselves to the new server?

also since bravo1 is configured as the source server for the address spaces on the bravo org, do i need to change this? what else should i look for in the organization that points to either alpha1 or bravo1?

thank you,


Yes CPU Cores.

Yes you can place logs and DB on the same drive since Exchange performce sequential IOs all the time.

such a huge mailbox is not recommended, the biggest maximum is 10 GB for 2010, but this is not from technical perospective but rather performance wise.

you can move the users directly from the 2003 to 2010.

Regards, Mahmoud Magdy Watch Arabic Level 300 Videos about Exchange 2010 here: Read pretty advanced Exchange stuff I post here:, follow my blog: , corp blog: and if you Liked my post please mark it as helpful and accept it as an answer


how do i know how many core cpu i need for the mailbox server?


thanks gavin and busbar. What do I do with the send connectors for the other 2 servers ? i want to make bravo2 hte main exchange and remove the bravo1 and alpha1 and alpha2.


Hi Roy,
If you finish all the migration produces, you could remove the connectors and create new connector on the bravo2 for outbound email.
You must remove all the connectors which set the server as an end when you remove the old servers.
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