What is the impact of enabling Fault Tolerance on VMs?

Enabling Fault Tolerance on virtual machines (VMs) allows for continuous availability by creating a secondary instance of a VM that is a live replica of the primary one. This setup provides protection against hardware failures by ensuring that if the primary VM experiences a failure, the secondary VM can take over almost instantaneously, preserving the state and execution of the applications.

However, this configuration can indeed reduce performance. When Fault Tolerance is enabled, the primary and secondary VMs continuously synchronize their operations. This synchronization process demands additional resources such as CPU and memory, which can lead to increased latency and decreased overall performance of the VM. The resources required for maintaining this real-time copy can strain the available resources of the host system, especially if multiple VMs have Fault Tolerance enabled.

While other factors like additional storage requirements can come into play, the core performance impact from the constant replication process is significant when evaluating the practical effects of enabling Fault Tolerance on VMs.