When an ESXi host fails, the VM’s which were running on that ESXi are restarted on remaining nodes in the cluster. But how HA KNOWS that how many VM’s were running on the host before it has failed. The answer is:

HA takes help of 2 files namely “power on” and “Protected LIST”. The “power on file is maintained by each ESXi host individually and it contains entries of those VM’s which are currently running on that ESXi. The “Protected list” file is maintained at datastore LEVEL and tells HA that what were the VM’s which were protected before the failure. On the basis of contents of these 2 files HA takes decision of restarting VM’s.

When a VM is powered off MANUALLY then entry of that VM is removed from “Protected list” file so that HA do not accidently restart that VM also.

When an ESXi host fails, the VM’s which were running on that ESXi are restarted on remaining nodes in the cluster. But how HA knows that how many VM’s were running on the host before it has failed. The answer is:

HA takes help of 2 files namely “power on” and “Protected list”. The “power on file is maintained by each ESXi host individually and it contains entries of those VM’s which are currently running on that ESXi. The “Protected list” file is maintained at datastore level and tells HA that what were the VM’s which were protected before the failure. On the basis of contents of these 2 files HA takes decision of restarting VM’s.

When a VM is powered off manually then entry of that VM is removed from “Protected list” file so that HA do not accidently restart that VM also.