The cluster is yellow due to a shortage of resources.

If the cluster does not have enough resources to satisfy the reservations of all resource pools and virtual machines, but does have enough resources to satisfy the reservations of all running virtual machines, DRS continues to run and the cluster is yellow.

A cluster can become yellow if the host resources are removed from the cluster (for example, if a host fails).

Add host resources to the cluster or reduce the resource pool reservations.