Hi,

With Exchange 2013 is it possible to run 2 "front-end" CAS servers without a load balancer (and just do round robin DNS)?  This would be in a set up with 2 backend DAG members.

We did this with 2007 but reading about putting the DAG members in maintenance mode got me thinking about some sort of maintenance mode for the CAS only servers (which doesn't seem to exist).  And that got me thinking of the implications of doing a CU on one of the CAS members while being live.

Thank you,

Kurt

Hi Kurt,

Exchange 2013 support 'single global name space' as I have explained here in my blog: http://exchangeonline.in/single-global-namespace-support-in-exchange-2013/

Hi,

With Exchange 2013 is it possible to run 2 "front-end" CAS servers without a load balancer (and just do round robin DNS)?  This would be in a set up with 2 backend DAG members.

We did this with 2007 but reading about putting the DAG members in maintenance mode got me thinking about some sort of maintenance mode for the CAS only servers (which doesn't seem to exist).  And that got me thinking of the implications of doing a CU on one of the CAS members while being live.

Thank you,

Kurt

You can use DNS load balancing internally but honestly it doesn't give you any protection when a node goes down. In other words you have 50/50 shot of going to a CAS that is running vs a CAS that is down.  Layer 7 load balancing would help prevent that.

Why are you looking at separating out the roles?  Most of the current deployment guidance is deployment of multirole servers.

Thanks.

We went with a recommendation to deploy separate servers for performance reasons.

Kurt

Can you expand on that Kurt, as that should not be the case.

Well it was just a matter of concern that we felt the mailbox servers would be loaded enough, and we didn't want to put any additional load on them.  Are you saying putting the CAS role on a mailbox server doesn't really add any load?

There is conflicting information out there, and we probably found it while planning.  For instance just today I happened upon a TechNet site that recommends a front-end back-end config:

http://blogs.technet.com/b/get-exchangehelp/archive/2013/02/07/managing-exchange-2013-iis-virtual-directories-amp-web-applications.aspx

I know that is from 2013, but a lot of the initial deployment articles are from then.  I hadn't consulted this forum before deployment, and now I have seen various recent posts about combining the roles.

What are the disadvantages of running separate servers for the roles?

Thanks,

Kurt

This is what we have asked customers to deploy with Exchange 2010 and 2013.  The below link should answer your questions.

http://blogs.technet.com/b/exchange/archive/2014/04/21/the-preferred-architecture.aspx

The option to split roles is not longer present in Exchange 2016, there is the mailbox server. 

I pinged Craig, the author of the post you mentioned, and asked him to tweak that section. 

To add to what Rhoderick mentioned, if you deploy CAS only role servers, you will find it to be tremendous waste of resources, licenses and management time. 

Dont forget to size based on the calculator!

https://gallery.technet.microsoft.com/office/Exchange-2013-Server-Role-f8a61780

Thanks guys - interesting PA article.

Kurt