What defines a virtual machine (VM) affinity rule?

A virtual machine (VM) affinity rule specifically allows certain VMs to run on the same host. This is particularly useful in scenarios where VMs have dependencies on each other, such as applications that require low-latency communication or shared storage. By ensuring that these VMs are housed on the same physical host, their performance can be optimized, and overheads associated with inter-host communication can be minimized.

Affinity rules help maintain the desired architecture for applications, ensuring that related services can efficiently interact and operate seamlessly without the delays that occur when VMs are spread across multiple hosts. This feature is critical for maintaining application performance and availability in a virtualized environment.