I am designing a new exchange org with a backend cluster, two smtp servers and two owa servers. I am confused as to which server the HUB role is supposed to be on. Client use third party provider for all spam, content management etc... Thanks,

Also can anyone explain to me how you set up OWA and SMTP servers? Prior to 2007 you would specify the "this is a front end server" checkbox. Now how do you designate the front end servers? Is it done the same way? Thanks,

OWA is running on your CAServers. CAS is doing what the FE server used to do and some more. HUB servers is doing the mail transport, both SMTP and inside the store http://msexchangeteam.com/archive/2006/09/12/428880.aspx

Lasse,Thank you for that reply, but what about the original question. I am curious about it as well. For instance, if I have an edge in the DMZ, a dedicated CAS and dedicated Mailbox server, and do not want a dedicated HT server, where should the HT role go? On the Mailbox server or the CAS?Narizz

On the CAS will be a good option.

Totally agree the CAS and HUB on one server should be no problemRegards,Johanblog: www.johanveldhuis.nl

Johan,I see that done alot and am wondering why there and not on the Mailbox Server? Is it a processing and memory issue having the information store on the same server as the HT? I also wonder about the network overhead of putting the HT on tha CAS (client access competing with mail delivery on the same NIC). Do you have a specific reason for putting the HT on the CAS?Narizz

Since you are trying to install Clustered Mailbox servers (SCC/CCR)... so you cant put HUB/CAS on that.Check the below article on how to Deploy Server Roles http://technet.microsoft.com/en-us/library/aa997610.aspx

Hari,For CCR, I completely agree as you cannot share hardware between a clustered mailbox server and any other role and the HT can also server as the file share witness. However, in the example specified above, I did not mention any replication. If there is no replication in the environment, does it not make more sense to install the HT on the mailbox server itself so message stream straight from the edge to HT and then to the Mailbox, skipping a networking hop. This, of course, assumes the Mailbox/HT server has the hardware to keep up (processor, memory, etc). Do you see any flaw in this thinking?Narizz

If its not Clustred theres no flaw in installing M/H/T/C roles on one server..... and Edge on a different box... no doughts in it and its a acceptable solution from Microsoft.

Well the only difference is that if you have a hub transport and MAilbox server installed on the same machine , then all the emails sent from users having mailbox in that server will use the Locally installed hub for transport.Consider You have two serversserver 1 name : MH , having Mailbox and Hub installed. server 2 name : HC , having HUB and CAS installed,then all the emails will be routed from server 1 having HUB and mailbox installed. server 2 hub role will never be used.regardsAli

It should also be noted that the Mailbox and the Hub Transport roles are more I/O intensive than the CAS role, which is why if you are concerned about performance, or if you are supporting many users it is often better to marry the CAS/Hub Transport role or seperate the roles onto their own servers. The Hub is responsible for message flow, and will operate a database to hold the messages whilst they are in a transient state. This places a certain I/O overhead which should be considered when sizing for the Exchange server roles. Take a look at the following articles for some interesting reading:http://technet.microsoft.com/en-us/library/aa996719.aspx, http://technet.microsoft.com/en-us/library/bb738142.aspxandhttp://www.msexchange.org/articles-tutorials/exchange-server-2007/planning-architecture/exchange-2007-sizing-cheat-sheet.htmlShaun