Memory Total on the RM UI is not refreshed until an application is launched. This is a problem when the cluster is started for the first time or when there are any lost/decommissioned NMs.
When the cluster is started for the first time, Active Nodes is > 0 but the Memory Total=0. Also when there are any lost/decommissioned nodes, Memory Total has wrong value.
This is a useful tool for cluster admins and has to be updated correctly without having the need to submit an app each time.