Mixing CPU/Server Generations in a vSAN Cluster – What’s Supported?

When designing vSphere clusters, vSAN or not, its pretty common knowledge that the hardware should match as much as possible. This includes the server make and model, CPU/RAM configuration, HBA, disks, NICs etc. There are times when this is not possible, or doesn’t make sense. Examples would be when the servers in your cluster are EOL or you know they will be soon and you would rather purchase the newer server generation than buy hardware that will soon not be supported by the manufacturer.

I recently asked my local vSAN SE if VMware had an official stance regarding mixing server or CPU generations in a vSAN cluster. His response was that he certainly wouldn’t recommend it but he stopped short of saying mixed configurations would not be supported. We didn’t have enough time to discuss further so I basically walked away with the attitude that I would have to ensure that whenever I was designing a vSAN cluster for a customer I would ensure that I was using hardware that they would be able to easily duplicate for the next few years should they have the need to expand their cluster.

Fast forward to this week when this question was brought up by another individual on the vExpert Slack channel and it cause a bit of a debate. Several of us were discussing this and we basically came to the conclusion that we could not find an official VMware stance on this. Some of the documentation found on storagehub.vmware.com gave some guidance but nothing definitive.

So assuming you can keep everything the same aside from CPU/motherboard does vSAN care? The conclusion we came to during this discussion is that as long as you are using EVC then vSAN shoudln’t care. It is certainly considered best practice to keep hardware identical whenever possible. It is important to be mindful when mixing CPUs that vSAN will essentially be bound by your weakest CPU when serving IOs in this type of scenario.

During the conversation a couple of VMware employees chimed in and confirmed that as long as you are keeping CPU/RAM/Storage balanced accross hosts in the cluster, it shouldn’t matter. There was even an implication that this is officially documented somewhere but I have not been able to find any source for this as of yet.

Bottom line, when expanding a vSAN cluster keep the hardware identical if possible. When its not possible pay close attention to the hardware in the new hosts and make it as balanced as possible.

My VMworld 2017 Experience

August 2017 marked the first VMworld that I was able to attend in person. After years of hoping to attend, I was fortunate to obtain a free pass due to my community involvement. Additionally I started a new job in April of 2017 and as a condition of accepting my new employer’s offer I requested that they put in writing that they would pay my travel and expenses to attend VMworld 2017 in Las Vegas.

VCDX Workshop

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With that all behind me I was off to Vegas! I flew out earlier than most so that I could take advantage of the VCDX Workshop on the morning of 8/26/2017 that we being run by Joe Silvagi (@vmprime).

This was a great workshop that illuminated the process involved in becoming a VCDX, but more importantly helped me learn how to get into the mindset of an IT architect. Best of all, its free!

After spending over a decade working primarily in roles of IT administration and engineering I am now trying to live up to the title of Architect. I am primarily responsible for infrastructure design on a daily basis as opposed to the operational responsibilities that I have previously held. The VCDX is the premier IT Architect certification in the world and this workshop provides tremendous value to anyone seeking to improve their skills as an architect, regardless of whether they plan on pursuing a VCDX certification. I would encourage checking the VCDX program calendar if you are interested in attending one of these workshops in person or online.

I am currently so far from obtaining a VCDX that it is not even on my long term goals list at this time. I currently hold a VCP5-DCV so I plan on first passing the VCP6 delta exam then pursuing both the VCAP6-DCV Deploy and Design certifications. After that I will evaluate whether I have the desire, time, and funds to create a design and submit it for VCDX defense.

Community Events

Before VMworld officially kicked off there was one more important activity that I was involved in. Dodgleball! More specifically #v0dgeball according to the community. This was a very fun event and more importantly it raised money for a good cause, the Wounded Warrior Project. I was fortunate enough to participate with the VMUG team along with several of my fellow VMUG leaders. We came in 3rd out of 9 teams and had a blast.

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After #v0dgeball I spent a bit of time in the Solutions Exchange on Sunday night before heading over to the VMUG party. This party was a blast and more importantly everyone now knows what a goofball I am as I took home the VMUG lipsync battle crown.

 

The Conference

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The keynotes from Day 1 and Day 2 were very enjoyable to me, mostly because I viewed them from the hang space as opposed to making the trek to the events center.

The rest of the conference was kind of a blur. I did attend several sessions but I spent most of my time in the VMvillage and Solutions Exchange.  The VMvillage was a great place to get to know many of the folks in the community that I had previously only known via twitter.

The VMTN community stage was located here and I was proud to participate in the vBrownBag tech talks, both with my own session about Automating Repetitive tasks in Veeam Backup and Replication and also Wednesday morning’s vExpert daily panel. I also viewed many session while I was there. If you missed them they are thankfully all on vBrownBag’s YouTube page.

The Aftermath

I have personally gotten incredible value out of attending VMworld 2017 and hope to attend next year as well. In they days and weeks following the conference, when I’m not busy catching up on work, I have been spending a lot of time watching all the sessions I missed on the VMworld YouTube page. Additionally the vBrownBag tech talks mentioned previously are a great way to get caught up on all the community goodness that happened during the conference.

If you are in the Indianapolis area, be sure to keep a look out for an announcement from Indy VMUG. We are in the midst of planning our Q4 2017 meeting and will be including plenty of information from VMworld 2017 for those who were not fortunate enough to attend.

First blog post

I just got back from VMworld this week and have spent most of my time catching up on work.  I did want to get started blogging though as its been on my todo list for months now. At this point its more about learning the platform that actually spewing content so don’t expect a sprint out of the gates with articles.