Per-VM EVC

EVC Mode & CPU Compatibility: The “Lazy Admin” FAQ

Posted on Updated on


You’ve just unboxed a shiny new host with the latest Intel or AMD processor, but your current cluster is running hardware from three years ago. You try to vMotion a VM, and vSphere gives you the dreaded “CPU Incompatibility” error.

Enter Enhanced vMotion Compatibility (EVC). Here’s everything you need to know to get your mixed-hardware cluster working without the headache.

What exactly is EVC?

Think of EVC as a “lowest common denominator” filter for your CPUs. It masks the advanced features of newer processors so that every host in the cluster appears to have the exact same instruction set. This allows VMs to live-migrate between old and new hardware because the “view” of the CPU never changes.

Quick FAQ

Q: Can I mix Intel and AMD in the same EVC cluster? A: No. EVC only works within a single vendor family. You can mix different generations of Intel, or different generations of AMD, but you cannot vMotion between the two brands.

Q: Will EVC slow down my new servers? A: Technically, yes—but rarely in a way you’ll notice. It hides new instructions (like specialized encryption or AI math sets), but the raw clock speed and core count of your new CPUs are still fully utilized. Most general-purpose VMs don’t use the high-end instructions being masked.

Q: Do I need to power off VMs to enable EVC? A: It depends:

  • Enabling on an empty cluster: No downtime.
  • Enabling on a cluster where VMs are already running on the oldest host: Usually no downtime.
  • Enabling on a cluster where VMs are running on newer hosts: You must power off those VMs so they can “re-boot” with the masked CPU instructions.

Q: What is “Per-VM EVC”? A: Introduced in vSphere 6.7, this allows you to set the EVC mode on the VM itself rather than the whole cluster. This is a lifesaver for migrating VMs across different vCenters or into the Cloud (like AWS/Azure).

How to Find Your Correct EVC Mode

Don’t guess. Use the official tool:

  1. Go to the VMware Compatibility Guide (CPU/EVC Matrix).
  2. Select your ESXi version.
  3. Select the CPU models of your oldest and newest hosts.
  4. The tool will tell you the highest supported “Baseline” you can use.

Step-by-Step: Enabling EVC on an Existing Cluster

  1. Select your Cluster in vCenter.
  2. Go to Configure > VMware EVC.
  3. Click Edit.
  4. Select Enable EVC for Intel/AMD hosts.
  5. Choose the Baseline that matches your oldest host.
  6. Validation: vCenter will check if any running VMs are currently using features above that baseline. If they are, you’ll need to shut them down before you can save the settings.

Summary Table: EVC Baselines

If your oldest host is…Use this EVC Mode
Intel Ice LakeIntel “Ice Lake” Generation
Intel Cascade LakeIntel “Cascade Lake” Generation
AMD EPYC RomeAMD EPYC “Rome” Generation

This entry was posted in VMware and tagged , , , , , , , , , , , , , , , .