Robert’s Rules of Exchange: Multi-Role Servers

I'd like to thank Tony Redmond for the great post in reference to this Robert's Rules post.  I suggest reading it (and following Tony's blog, for that matter).  Check it out here:  http://thoughtsofanidlemind.wordpress.com/2011/04/12/microsoft-reveals-the-truth-about-single-role-servers/

One question Tony asks in his blog is "what's happened in the five years since to make Microsoft recant" the idea of having the roles separated.  The big thing here is that with the advent of CCR in Exchange 2007 as the high availability (HA) model of choice, the Exchange team didn't support having the roles other than Mailbox on the CCR machines (or even on an SCC cluster machine, for that matter).  Our customers pushed back on this because in many cases it did cause a higher number of servers in an organization.  As we moved from CCR in Exchange 2007 to the DAG in Exchange 2010, Microsoft decided to support the other roles when on the DAG nodes.

In my article above, we talk a lot about simplicity and how the multi-role server can simplify your Exchange implementation no matter the size of your organization.  What we really don't touch on is the fact that the multi-role server can also make better use of the newer hardware.  Processors now have 6 or 8 cores per processor, and making use of those high core counts with a single role server is sometimes difficult.  The multi-role server allows a higher processor density in a given server platform - having a server that supports 2 processor sockets with a single processor installed takes space in your datacenter and generates almost as much heat as it would if it had both processors, so why not make full use of the hardware in your system.

The only thing I would like to refute in Tony's blog article is the claim that somehow this had something to do with marketing.  Marketing has nothing to do with the technical recommendations we make around high availability.  The high availability technologies and how to deploy them have been a steady progression of revolution and evolution from Exchange 2003 with only what was later known as single copy clusters to Exchange 2007 with CCR to Exchange 2010 with the DAG.  The requirements and the recommendations around these HA technologies have changed with the versions.  But, as I teach in every course I ever teach around HA of Exchange - we don't deploy them because they are cool or snazzy or because Marketing wants it done.  You only deploy CCR or DAGs because you need the HA or the site resilience that DAGs bring.  If your customer requirements are such that you do not have a firm HA or site resilience requirement, then why deploy a DAG?  I will have very frank discussions with customers that want to deploy HA because their CIO has been reading CIO magazine again and thinks they need it when the business model is such that they have no hard requirement for it.

Thanks again, Tony!  Great blog!!