Updated – Exchange 2013 DAG, Windows Server 2012 R2 and VMware vSphere? Check support!
UPDATED 28/3/2024: See update below article.
A little heads up. While working on an extensive design including Exchange Server 2013 with Service Pack 1 installed on Windows Server 2012 R2, my eye caught a comment in the Facebook group Exchange Server 2013 (Facebook login required).
VMwares vSphere 5.1 and higher are shown to be validated by Microsofts Server Virtualization Validation Program (SVVP) to run Windows Server 2012 R2 VM’s. The hypervisor needs to be validated also as a requirement for virtualizing Exchange Server 2013. So far so good.
But you’re not there yet, the Microsoft Clustering on VMware vSphere: Guidelines for supported configurations (1037959) from VMware has a small footnote for this specific combination of Exchange and Windows OS. It’s only supported from vSphere 5.5. This is something that is easily missed (yeah, I would've missed it too if it weren’t for my procrastination on Facebook ). See the screenshot below with highlighting the specific sections (Click to enlarge image).
I’ve discussed this with an VMware vExpert and although he didn’t know any specifics, it might have to do with some improvements for low-latency applications specific for vSphere 5.5. New features in 5.5 might also explain why for Windows Server 2012 it is stated that (among others) a DAG does not require explicit support statements from VMware.
Luckily we are still in the designing phase, so we can and will take this into consideration (either upgrade vSphere or use Windows 2012 R1). Even if it would work, I wouldn’t want to take the risk ending up in an unsupported situation (from VMware). Especially considering that when you implement a DAG, high availability of Exchange servers is something that is on your mind.
This is a good reminder to always thoroughly check support from all vendors before implementing the newest builds and versions.
UPDATED 28/03/2014: We submitted a VMware support ticket with this issue. Their answer clarifies the statements made in the KB: The combination 2013 DAG on Windows Server 2012 R2 hasn't been tested by VMware on other than vSphere 5.5, but it certainly doesn't mean that other combinations won't work. Either way, their support also stated that an explicit support statement isn't required from VMware when we decide to use vSphere 5.1 in this situation instead. That is in line with the support statements in the KB article for Windows Server 2012 RTM and it makes me feel more comfortable to go forward (without vSphere 5.5). But don't believe me at my word; I would advise to submit a VMware support ticket if you also want an explicit clarification directly from VMware.