1. A method for locating cached data corresponding to data in persistent memory within a data storage facility, comprising: receiving a request for data in persistent memory; applying a function to a persistent memory address of the requested data to determine an address of one of a plurality of cache tag controllers, each of which controls nonduplicative cache tags; and looking up, at the addressed cache tag controller, a cache memory address for data corresponding to the requested data, wherein at least some of the cache tag controllers contain cache tags for less than all of the cache memory.