1. A method of collaborative management in a non-volatile hierarchical storage system including multiple controllers, the method comprising: a first controller receiving health reports from at least second and third controllers of the storage system regarding health of multiple storage units of physical storage under control of the second and third controllers; the first controller maintaining a health database of information received in the health reports; in response to a health event and based on information in the health database, the first controller modifying logical-to-physical address mappings of one or more of multiple storage units under its control such that data having greater access heat is mapped to relatively healthier storage units and data having less access heat is mapped to relatively less healthy storage units; and thereafter, the first controller directing write requests to storage units under its control in accordance with the modified logical-to-physical address mappings.