Best way to allocate 8 vCPU to a VM

[TonyJK]

Hi

We are g to set up MS RD Gateway Server for around 120 licence.  MS recommend 1 CPU allocated to 15 users.

In this way, 8 vCPU is required.  Would it be a problem if we set up such VM or is there any other suggestions ?

Thanks

[TonyJK]

I find this article and 50 users are supported by the RD Gateway Server.

RDS Host Virtual Machine Configuration

[NicolasAlauzet]

Hi there!

Provide ESXi version (vNUMA changes for example for esxi 5.5 to 6.x) and hardware specs.

[TonyJK]

Dear Nicolas,

We are running vSphere 6.0 Update 3 in a Cluster of 2 ESXi Hosts.

It is running on a DELL PowerEdge R530

2 Sockets

12 Core Per Socket

Logical Processor 48

May I ask where can I find out vNUMA Settings ?

Thanks

[NicolasAlauzet]

You may find this documents interesting:

Virtual Machine vCPU and vNUMA Rightsizing - Rules of Thumb - VMware VROOM! Blog - VMware Blogs

https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/techpaper/vmware-perfbest-practice...

Its usefull to understand how esxi handles cpu allocation

[NathanosBlightc]

Hi

When you need 8 vCPU for your VM, you need at least 8 logical processors in the ESXi host. Basically no matter how it's provided by the physical CPU sockets, different schemes just can made different performance rate for virtual machines.

[TonyJK]

Dear Amin,

May I confirm

1) It is possible for us to assign 8 vCPU to that VM ?

2) We can assign 4 sockets and 2 core per socket OR 2 sockets and 4 cores per socket OR 1 socket and 8 core per sockets ?  Is there any preference ?

Thanks

[NathanosBlightc · Accepted solution]

Based on your server infromation, yes of course you can do it ( 2socket*12core=24 logical core and with enabling hyper-threading you have 48 core)

Choosing between 2*4 or 4*2 or another processor structure will affect on the VM performance and is highly depend on many factors like the following:

1. Physical server structure and existing CPU sockets and cores

2. VM guest OS limitation and support of CPU

3. Requirement and architecture of your application/Service that has been installed on your VM

It's good to read the following links:

1. VMware Knowledge Base

2. world-line

3. And also my post in my personal blog: Virtualization Tip1: Relation between physical CPU & virtual CPU

[TonyJK]

Dear Amin,

Many thanks for your advice and I have done some research.

1) Windows Server 2008 R2 supports up to 64 physical processors or up to 256 logical processors per system.  Standard Edition supports up to 4 sockets (In this way, there is no problem to assign either 2 x 4 or 4 x2  vCPU to it).

2) Do I need to check the NUMA setting of server ?

For a Testing VM running Windows Server 2008R2, I have already assigned 2 x 4 vCPU and 20GB RAM to it.  It starts up properly.

May I ask is it necessary for me to add any Configuration Parameter manually ?  Is there any Configuration Parameter that has been added / changed as I assign 8 vCPU to that VM (Like the parameter numa.vcpu.min) ?

Thanks again

[NathanosBlightc]

I think it's better to don't change the VM advanced settings for vNUMA configuration, until you faced with large memory consumption. Please read this post about the NUMA structure from Frank Denneman and also vmware docs and its sub-link about control of vNUMA

[TonyJK]

Dear Amin,

My manager would like to add 4 more vCPU to the VM.  In this way, 12 vCPU will be allocated to it.

1) May I ask which combination of Socket / Core should I use ?  2 x 6 or 3 x 4 ... etc ?

2) Is there any other configuration parameters I need to change manually ?

3) Is there any pitfall for allocating so many vCPU to a VM ?

Thanks again.

[NathanosBlightc]

1. I prefer to use 2*6 combination because instead of 3*4 most of times using "even numbers" will reflect better performance ...

2. Basically no. While you don't need any special advance setting, do not modify their parameters.

3. It's based on architecture of your OS & its related application, check their design documentary.