Hosts are automatically added to the blocked hosts list if the service cannot be started and initialized on a host and the service retry limit specified in the application profile has been exceeded.
A blocked host is no longer available as a resource for that application. The advantage is that the system does not continuously try to start services on a host that is lacking vital software or hardware requirements. If you modify your application profile or upgrade your application in any way, the list is cleared and all hosts previously on the blocked hosts list are now eligible to have services started on them.
Cluster administrators can view and unblock hosts for a particular application associated with a consumer.