Newbie Questions about Vcenter and Vsphere - Creating single virtual machine that use processors from separate hosts?

[andrejbranch]

I have not purchased any vmware products yet, but I'm in the process of figuring out if vmware vcenter and vsphere are appropriate solutions for my group.

As far as I know, vcenter is a manager in which i can create and monitor vspheres across multiple servers. My question specifically is can vcenter create a virtual machine that uses resources from multiple servers. For example, can I create a virtual machine that uses 1 core from 1 server and another core from a separate server. Scaling that out, is it possible you could you have 5 servers with 10 cores each and create 1 virtual machine with 50 cores?

Thanks in advance

[vuzzini]

Hello andrejbranch,

Welcome to VMware community.

vCenter is an application to manage 2 or more ESXi Servers (depending on your configuration). You can create VM's on an ESXi host, so for example you need to create a VM from vCenter Server, ESXi host object needs to be selected from vCenter Hosts & Clusters view and then select Create New Virtual Machine.

vCenter Server displays the set of computing resources that run on a particular host, cluster, or resource pool. Using the Hosts & Clusters view in vCenter Server, you can manage the and organize your inventory of computing resources. The VM's are eventually created on an ESXi host as explained earlier.

To answer you question about CPU cores, you cannot create a VM that uses 1 core from 1 server and another core from a separate server as the VM will always run only on a specific ESXi server at a specific time.

[andrejbranch]

Thank you vuzzini for the quick reply,

Let me ask a bit more then. I'm basically curious how vmware vcenter and vsphere can help me run processes across many many processors.

From what you said I understand that ESXi servers are what the vm's run on, meaning you can only have a VM with as many cpu's as the ESXi server has right?

Does this mean I have to have a very beefy ESXi server to have VM's with many processors?

Thanks again

[Linjo]

Yes, almost. Most CPU:s now have more then one core, in ESX each of the cores are considered as a CPU. (pCPU)

So if you have a host with 2 CPU:s with 6 cores each then you have 12 pCPU:s available for your virtual machines on that host.

Hope this helps.

// Linjo

[rcporto]

From what you said I understand that ESXi servers are what the vm's run on, meaning you can only have a VM with as many cpu's as the ESXi server has right?

The vCPU of a VM coming from an unique host, not from multiple hosts. The number of vCPU that you can assign to a VM depends of the number of logical processors on the host, license, gust OS support, etc. But the number of vCPU cannot be more than logical processors of the host. Take a look at the official documentation for vCPU limitations: vSphere 5.5 Documentation Center

Does this mean I have to have a very beefy ESXi server to have VM's with many processors?

If your VM is really CPU intensive, this maybe is not a good candidate for virtualization... anyway I recommend you start using a small number of vCPU and add more if needed.