To check on the HA status of the cluster you can go to “Host and Clusters” view - then Select a cluster - then to go the “Summary” tab - and under the “vSphere HA” Section - select “Advanced Runtime Info”. Problem When you select the Host Failures Cluster Tolerates admission control policy, the Advanced Runtime Info link appears in the vSphere HA section of the cluster's Summary tab in the vSphere Client. The Advanced Runtime Info box might display a smaller number of available slots in the cluster than you expect. Slot Size is defined as the memory and CPU resources that satisfy the reservation requirements for any powered-on virtual machines in the HA cluster.This article is just to cover how the HA slots. VMware HA Slot is the default admission control option prior to vSphere 6.5.
With this policy, when a host fails, vSphere HA attempts to restart its virtual machines on the specified failover host, which under normal operating conditions remains unused. Finally, with the Specify a Failover Host admission control policy, you can configure vSphere HA to designate a specific host as the failover host.
