For most who remember their first virtualization experience, the VMware vMotion process was the moment when they knew that virtualization was here to stay because VMware EVC Mode technology is directly related to vMotion. The term EVC stands for Enhanced vMotion Compatibility.
The whole purpose of VMware EVC Mode is to enable virtual machines to migrate between ESXi hosts in the same cluster running different processor architectures. VMware EVC Mode can mask it with instructions for CPU features.
VMware EVC mode grants users per VM EVC mode, as an EVC baseline is needed to configure EVC mode settings. On the other hand, changed EVC mode settings can give CPU instructions for the latest ESXi version.
Therefore, they seem the same throughout the vSphere cluster, which may contain several different core processor architects in each ESXi host. As you might expect, this procedure allows you to do things that you would not otherwise be able to do when scaling your vSphere clusters.
How Does VMware EVC Mode Work?
VMware EVC Mode works well for the cluster and will allow you to set specific CPU model types and instructions at the cluster level. VM EVC mode brings up a VMware EVC feature and VMware EVC compatibility as EVC settings need to be previously determined.
We аrе already aware that the ESXi hypervisor can be virtualized by the CPU, memory, storage, etc. VMware compatibility guide is what you need (here on VMware-ESXi.com). EVC configuration
Because the hypervisor abstracts the actual physical processor from the virtual machine and controls it through an abstraction layer, vSphere can control which processor instructions are presented on hosted virtual machines.
When you enable EVC at the cluster level, all hosts in the cluster are configured to display CPU characteristics from the type of processor selected by the user of all virtual machines running in the cluster.
Identical CPU features are displayed on virtual machines regardless of which host they are running so that virtual machines can migrate to any host in the cluster. It allows vMotion compatibility to be ensured between ESXi hosts.
It ensures CPU compatibility for vMotion operations, although the underlying hardware may differ from one ESXi host to another. The main benefit is adding servers with the latest processors to your existing cluster (s) seamlessly and without interruption.
Even more significantly, EVC provides you with the flexibility to increase your infrastructure, reducing the need to deactivate older servers impulsively and maximizing ROI. It also paves the way for flawless cluster upgrades once the decision to retire old hardware is made.
Innovative microprocessor features and instruction sets are often included when a new family of processors is launched. These features include performance enhancements in multimedia, graphics, or encryption.
With this in mind, try to determine the type of applications you will run in your vSphere environment. It presents you with a rough idea of the type of processors you will need.
It allows you to pre-determine the applicable EVC modes when mixing servers with processors of different generations. EVC modes also depend on the vCenter server version.
CPU compatibility for vMotion
To run vSphere vMotion, the processors in both hosts must be compatible. The processors must be from the same vendor, be in the same family, and support the same features. Yet, some Intel and AMD hardware extensions can help alleviate CPU differences.
You must manually enable EVC mode at the VMware vCenter Server level to allow node computing from different CPU architectures in the same cloud group.
When a VM migrates between ESXi hosts, the VM has already detected the type of processor it runs on when booting. Because the VM does not reboot during the vMotion process, the guest assumes that the CPU instruction set on the target host is identified as the source host.
Consequently, the processors in the two hosts that perform vMotion must meet the following requirements:
- clock speeds, cache size, hyperthreading, and number of cores – virtualized away by VMkernel
- manufacturer – Intel or AMD – instruction set contain many minor differences
- presence or absence of SSE3, SSSE3, SSE4.1 – multimedia instructions usable directly by applications
- virtualization hardware assist
- execution disable (NX/XD bit) – the guest operating system relies on NX/DX only if detected
Enable VMware EVC for the management cluster
When you add a new computing node to a cloud group and if the processor type of the computer node differs from the existing computing node of the cloud group.
It would also be helpful if you could enable this mode (Enhanced vMotion Compatibility EVC – VMware feature) via the VMware vCenter server. Please enable it to allow virtual machines to migrate between computed nodes of different processor types.
Here is what you need to do:
- Select the cluster in the inventory;
- Make sure the cluster does not include virtual machines;
- Turn off all virtual machine hosts with features more critical than EVC mode;
- Migrate cluster virtual machines to another host using vMotion;
- Because these virtual machines work with more functions than the EVC mode you intend to set up, turn off the virtual machines to migrate them back into the cluster after enabling EVC;
- Ensure the cluster contains processors with only one vendor, either Intel or AMD;
- Click the Manage tab, select VMware EVC, and click Edit;
- Enable EVC for the CPU vendor and the set of features suitable for the cluster hosts and click OK;
- If you have turned off or migrated virtual machines outside the cluster, turn on virtual machines in the cluster, or migrate virtual machines.
VMware EVC mode stands for VMware Enhanced vMotion Compatibility. VMware EVC mode is a VMware vSphere virtualization feature that allows virtual machines (VMs) to move between ESX/ESXi hosts on different processors.
VMware EVC mode conceals relevant CPU features that do not match all vMotion-enabled hosts, such as clock speed or kernel count. This feature works for different versions of processors from the same chip manufacturer.
Nevertheless, VMware EVC mode cannot enable vMotions between AMD and Intel processors. The VMware vCenter server checks for compatibility between the current and destination VMs before moving the active VM.
Although VMware vSphere allows users to hide CPU features from individual VMs using CPU compatibility mask settings, this is not recommended.
Improved vMotion capability may not always prevent VMs from accessing CPU functions, depending on how the virtual machine applications work. VMware EVC mode can also be enabled through VMware vCenter Server.