How to assign vcpu per sockets and enable NUMA settings on vmware vm.

Ghani

for enable numa , we need to set correct cpu cores per socket in vm ?/

scottalanmiller

@ghani said in How to assign vcpu per sockets and enable NUMA settings on vmware vm.:

@jaredbusch

for enable numa , we need to set correct cpu cores per socket in vm ?/

NUMA is always enabled. NUMA is just part of the system. What are you trying to accomplish? What is making you ask this question?

Ghani

@scottalanmiller

Customer have sap application running on vm. For better performane , need to enable NUMA settings on vm. How to enable NUMA on SAP VM with cpu per sockets

scottalanmiller

@ghani said in How to assign vcpu per sockets and enable NUMA settings on vmware vm.:

@scottalanmiller

Customer have sap application running on vm. For better performane , need to enable NUMA settings on vm. How to enable NUMA on SAP VM with cpu per sockets

But NUMA is always enabled. Why do you feel that "enabling" it is needed? What has led you to this belief?

scottalanmiller

Here is how to set CPU Affinity. But it should be obvious that you should not be doing this. VMware warns against doing this, you really need to know what you are doing and the reason you keep giving as to why you want to do this tells us that you don't know what it is for and are doing it at the wrong time.

For performance, you AVOID CPU Affinity.

https://pubs.vmware.com/vsphere-4-esx-vcenter/index.jsp#com.vmware.vsphere.resourcemanagement.doc_41/managing_cpu_resources/t_assign_a_virtual_machine_to_a_specific_processor.html

Ghani

@scottalanmiller

customer afraid about sap vm performance, because they dont have downtime of sap servers. sap vm best praticies need to assign specific vcpu cores per socket with numa enabled to helps to improve better performance,//

scottalanmiller

@ghani said in How to assign vcpu per sockets and enable NUMA settings on vmware vm.:

@scottalanmiller

customer afraid about sap vm performance, because they dont have downtime of sap servers.

Then they should NOT behave the way that they are. They should do the right thing, rather than just being crazy. They aren't acting like they are afraid of VM performance, they are acting like they are irrational.

And obviously they would be testing this ahead of time no matter what if this was important at all and these kinds of issues wouldn't be things to be questions.

Also, these issues don't cause downtime.

scottalanmiller

@ghani said in How to assign vcpu per sockets and enable NUMA settings on vmware vm.:

sap vm best praticies need to assign specific vcpu cores per socket with numa enabled to helps to improve better performance,//

That's not actually the best practice. You have misinformation. You are using VMware, VMware best practices apply because it is VMware and VMware alone, not SAP, that matters here.

Best practice is to not do what you are doing.

And it is nonsensical, since NUMA is enabled anyway. So whatever your source information is all messed up.

NetworkNerd

I'll throw in a couple of recommendations here as well. One thing you want to be careful of is not spanning a NUMA boundary with the number of vCPU you're giving the SAP VM as this can actually slow down the VM overall. Make sure you do not turn on hotplug CPU for the VM (ability to add additional vCPU with the VM powered on if supported by the guest OS) because it will disable vNUMA.

NetworkNerd

Also, I would highly recommend watching this session from VMworld 2017 about monster VMs that could help anyone needing to virtualize a DB server - https://www.youtube.com/watch?v=sXbOoRo_Wn4. You can get the slide deck here.