EVC Mode displayed for a powered-on VM without Per-VM EVC mode or Cluster level EVC mode enabled
Article ID: 343481
Updated On:
Products
Issue/Introduction
- EVC Mode displayed without EVC.
- Per-VM EVC mode is not configured in VM(s).
- Cluster-level EVC mode is not configured.
- Virtual machine reports "EVC Mode" data in vSphere Web Client.
Environment
Cause
"VMware EVC is Enabled" for a powered-on is displayed when the features required by a running VM are matched against some EVC modes.
Resolution
"VMware EVC is Enabled" may show an EVC mode for a VM even though there is no EVC mode configured for the Cluster or the VM. An EVC mode is displayed when the features required by a running VM can be matched against some EVC modes. Sometimes a match can not be found, in which case no EVC mode is displayed for the VM. This is an expected behavior.
- vCenter server only uses the set of features the VM requires after power on to tell if a Per-VM EVC mode is set, and it doesn't look at the VM's configuration file directly to determine this.
- All VMs lock in a set of features they require at power on, even if no Per-VM EVC or cluster EVC is configured.
- Per-VM EVC and Cluster level EVC are the recommended methods to control the set of features the VM requires prior to power on.
Below scenarios are applicable for the powered-on VMs where Per-VM EVC mode is Disabled and underlying ESXi host is not the part of any EVC mode Enabled cluster:
Scenario 1: "VMware EVC is Enabled" in vCenter UI for the powered-on VMs running on ESXi hosts with Skylake / Cascade Lake processors.
In this case, VM Hardware version 21 (HWv21) VMs running on older CPUs like Sky lake / Cascade lake, and HWv20 and older VMs will still show "VMware EVC is Enabled" after VM power on because they don't expose the new features to the VM and will match with one of the prescribed EVC modes.
Scenario 2: "VMware EVC is Disabled" in vCenter UI for the powered-on VMs running on ESXi hosts with Ice Lake / Cooper Lake, Sapphire Rapids / Emerald Rapids and Granite Rapids processors.
It's a combination of the newer host CPU generation, which includes new features, and the use of a newer VM Hardware version e.g. HWv21, which allows new features to be exposed to the VM.
Some of these new features aren't part of any of the prescribed EVC modes, so the vCenter UI won't match with any of them, and it will continue to display "VMware EVC is Disabled" for the VM's Per-VM EVC mode after Power-on.
The minimum EVC mode the VM can enter is as follows:
- If the VM is on a Broadwell host and power on, this VM can't migrate to a host less than Broadwell, nor enter an EVC cluster less than Broadwell.
- If the VM is on a Skylake host and power on, this VM can't migrate to a host less than Skylake, nor enter an EVC cluster less than Skylake.
- If the VM is on an Ice Lake host and power on, this VM can't migrate to a host less than Ice Lake, nor enter an EVC cluster less than Ice Lake.
To prevent this from happening, configure a Cluster-wide EVC mode suitable for the CPU generation. Refer this Technical Document for more details : How to Change the vSphere EVC Mode for Your Cluster
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