Pages that incur repeated hits in PROMOTE are highly likely to migrate upwards in the hierarchy as
they are subjected repeatedly to the
probability of migrating upwards.
The more the number of hits incurred by a page the more it can climb in the hierarchy. The most hit pages soon begin to accumulate in the topmost level.
Note that while DEMOTE uses inter-cache bandwidth for pages on their way up towards the application and also their way down, PROMOTE saves bandwidth by moving pages only in one direction.