Wrap Up - vCendol TechFriday! Season 1 Episode 2

It was time well spent during vCendol TechFriday! Game Night back at 6 December 2019. We played some scenario using VMware Hands-on-Lab, simulated some common CPU scheduling situation and looked at the impact. Using that information, now we know the consequences of such configuration which we can use in a design decision. I love the active discussion we had. I had FUN, and I hope you did too.

We started Game Night by simulating some common CPU configuration using VMware Hands-on-Lab platform. Our lab-captain Rakha Siswara, Solutions Engineer @ VMware, gave some tasks to audiences for each of them to try in their lab environment and record the results.

What we simulate was:

• Having a VM with number of vCPU equals to physical cores of vSphere host it resides.
• Doing oversubscription where the total provisioned vCPU from all VMs are more than the available physical cores of vSphere host it resides.
• Simulate some CPU load on the tests VMs and observe the impact on VM performance using benchmark tools, and CPU Ready value using esxtop.
• When all VMs loaded, CPU are oversubscribed.
• When only one VM loaded, another VM idle, CPU are oversubscribed.
• When only one VM loaded, another VM powered off, CPU not oversubscribed.
• Migrate tests VM to another host which has more CPU cores to avoid oversubscription, rerun the simulation scenario.

From that simulation, we discuss our observation, and note couple of things:

• Having a VM with number of vCPU equals to physical cores of vSphere host it resides will negatively impact on the VM performance due to CPU scheduling queue. This queue can be observed by looking at CPU Ready value using esxtop.
• This is true even though there's no other VM resides on the same host.
• Impact will be higher when there are other VMs resides on the same host, which create CPU oversubscription situation.
• It will be even higher when VMs are loaded.
• The same VMs gave higher benchmark value when migrated to host with more CPU cores with no oversubscription.

With those information, we know when we do host design we need to consider:

• The largest vCPU of a VM which will run on that vSphere host (or cluster) and then choose appropriate host with enough CPU cores to accommodate that VM.
• When designing for maximum VM performance, we might not able to gain the benefit of consolidation.
• On the other hand, designing for optimum consolidation might have impact on the VM performance delivered.
• Designing for virtualization will need to balance between performance vs consolidation which we want to aim.

And to top all the discussion, at the end of this first vCendol TechFriday! Game Night, we have our vCendol Warriors, Taufan Sangga and Harry Haryadi, which are the most active attendees, proofed by collecting the most gold (chocolate) coins which attendees get when they answer or ask questions, give thought, and complete their challenge.

CONGRATULATIONS for both vCendol Warriors!

Thank you for those who joined! And look forward for your involvement in our next vCendol TechFriday!

As a closing, please check this video to see it yourself how we had fun.