VMware ESX 3.5 - MRU policy and path persistence

Many VMware customers using storage arrays that use the MRU setting (EMC CLARiiON, Netapp, EVA, IBM DS series) policy find that after a certain period of time, their ESX servers are all using a single path, and a single array port - leading to degraded performance. This occurs in SPITE of careful manual balancing of the active paths.