Yesterday I was answering some question in the VMTN Forums when I noticed that someone referred to my article about Hybrid vs full Distributed vSwitch Architectures. This article is almost two years old and definitely in desperate need of a revision. Back in 2009 when Distributed vSwitches where just introduced my conclusion in this discussion was:
If vCenter fails there’s no way to manage your vDS. For me personally this is the main reason why I would most like not recommend running your Service Console/VMkernel portgroups on a dvSwitch. In other words: Hybrid is the way to go…
As with many things my conclusion / opinion was based on my experience with the Distributed vSwitch and I guess you could say it was based on how comfortable I was with the Distributed vSwitch and the hardware that we used at that point in time. Since then much has changed and as such it is time to revise my conclusion.
In many environments today Converged Networks are a reality which basically means less physical NICs but more bandwidth. Less physical NICs results in having less options with regards to the way you architect your environment. Do you really need you management network on a vSwitch? What is the impact of not having it on a vSwitch? I guess it all comes down to what kind of risks you are willing to take, but also how much risk actually is involved. I started rethinking this strategy and came to the conclusion that actually the amount of risk you are taking isn’t as big as we once all thought it was.
What is the actual issue when running vCenter virtually connected to a Distributed Switch? I can hear many of you repeat the quote from above “there’s no way to manage your vDS”, but think about it for a second… Do you really need to manage your vDS in a scenario where vCenter is down? And if so, wouldn’t you normally want to get your Management Platform up and running first before you start making changes? I know I would. But what if you really really need to make changes to your management network and vCenter isn’t available? (That would be a major corner case scenario by it self but anyway…) Couldn’t you just remove 1 NIC port from your dvSwitch and temporarily create a vSwitch with your Management Network? Yes you can! So what is the impact of that?
I guess it all comes down to what you are comfortable with and a proper operational procedure! But why? Why not just stick to Hybrid? I guess you could, but than again why not benefit from what dvSwitches have to offer? Especially in a converged network environment being able to use dvSwitches will make your life a bit easier from an operational perspective. On top of that you will have that great dvSwitch only Load Based Teaming to your disposal, load balancing without the need to resort to IP-Hash. I guess my conclusion is: Go Distributed… There is no need to be afraid if you understand the impact and risks and mitigate these with solid operational procedures.