Jamit200006
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Contributor

Moving VMs between Host of different cpu spec

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I am in the process of migrating a number of windows vms between some old infrastructure and new. The infrastructure is (cpu)Intel 2.4Mhz and the new is Intel 2.6Mhz. I am live vmotioning the VMs to limit any outage to the service.

The new infrastructure has newly provisioned VMs running at 2.6Mhz. My question is if I move the older VMs running at 2.4Mhz what is the impact on the new host cpu? Does it run at 2.4Mhz or does it run at 2.6Mhz?

I understand that the old VMs will run at 2.4Mhz until the VM's are shutdown. Interested what happens at the hardware layer.

I running Esxi 5.5u3.

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jhague
VMware Employee
VMware Employee

Hi, instructions should be executed at the underlying physical cpu speed. As far as I'm aware a VM can't dictate what speed something runs at on  the physical cpu as that is all offloaded to the hypervisor. Same principle with NIC speed.

When moving between different cpu families certain cpu features may be masked so as to ensure compatibility. EVC and CPU Compatibility FAQ (1005764) | VMware KB

John Hague http://linkedin.com/in/john-hague | twitter @jhague10 VCIX-DCV | VCP-DCV 3/4/5/6 | VCP6-NV | VCP7-CMA | VCAP7-CMA Design

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jhague
VMware Employee
VMware Employee

Hi, instructions should be executed at the underlying physical cpu speed. As far as I'm aware a VM can't dictate what speed something runs at on  the physical cpu as that is all offloaded to the hypervisor. Same principle with NIC speed.

When moving between different cpu families certain cpu features may be masked so as to ensure compatibility. EVC and CPU Compatibility FAQ (1005764) | VMware KB

John Hague http://linkedin.com/in/john-hague | twitter @jhague10 VCIX-DCV | VCP-DCV 3/4/5/6 | VCP6-NV | VCP7-CMA | VCAP7-CMA Design

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Jamit200006
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Contributor

Thanks I thought that would be the case but had a moment of doubt. So thought I'd ask.

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