Is it recommended to have different server hardware models in the same vCenter cluster?

By | January 28, 2023

It is generally not recommended to have different server hardware models in the same vCenter cluster.

This is because different hardware models may have different specifications, such as different CPU architectures, memory configurations, and storage capabilities.

These differences can lead to compatibility issues and can make it difficult to manage the cluster as a whole. Additionally, different hardware models may require different drivers and firmware, which can further complicate cluster management.

It’s better to have homogeneous servers with the same hardware models in a vCenter cluster for better performance and easy management.

However, it’s possible to do so with the help of vCenter feature called “Enhanced vMotion Compatibility” (EVC) which can mitigate the hardware differences and allows VMs to be vMotioned between servers of different hardware generations with minimal reconfiguration. This feature can be helpful in certain scenarios, such as when upgrading hardware or in a multi-tenant environment.

What is the role of Enhanced vMotion Compatibility in the VMware vCenter?

Enhanced vMotion Compatibility (EVC) is a feature in VMware vCenter that allows virtual machines (VMs) to be live migrated (vMotioned) between hosts that have different CPU generations. This feature works by creating a common baseline of CPU features that is supported by all hosts in a cluster, which ensures that the VMs running on those hosts are compatible with each other and can be moved between them without reconfiguration.

When EVC is enabled, vCenter automatically configures the CPU features of all hosts in the cluster to match the lowest common denominator of features that is supported by all hosts. This ensures that all VMs running on the hosts in the cluster are compatible with each other, and can be moved between them without interruption.

EVC can be especially useful in scenarios where you have a mix of older and newer hosts in the same cluster, and you need to upgrade the hardware but want to avoid the downtime associated with reconfiguring the VMs. Additionally, EVC can be useful in multi-tenant environments where different tenants may have different hardware configurations.

It’s important to note that EVC is not a permanent solution and it can’t add CPU features that aren’t supported by the host’s hardware, it only hides the unsupported feature, that’s why it’s important to have as similar as possible hardware in the cluster to minimize the impact of hidden features.

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