1. An apparatus comprising: a multi-tier memory structure comprising a plurality of non-volatile memory tiers each having different data transfer attributes and corresponding memory cell constructions; a data object storage manager adapted to generate first and second data objects responsive to one or more data blocks supplied by a requestor and to direct storage of the generated data objects in a first non-volatile tier of said memory structure, the first and second data objects having a common unit size; and a metadata storage manager adapted to generate first and second metadata units, the first metadata unit having a first selected granularity to describe the first data object, and to direct storage of the generated first metadata unit in a second non-volatile tier of said memory structure responsive to the first selected granularity, the metadata storage manager adapted to generate a second metadata unit having a second selected granularity to describe the second data object, the first and second metadata units being different, and to direct storage of the second metadata unit in third non-volatile tier of the memory structure responsive to the second selected metadata unit, the first, second, and third non-volatile tiers being different, the first and second selected granularities each identified responsive to an access rate of the respective first and second data objects and characterized as a resolution in terms of groups of bits of user data in the data objects individually described by respective metadata units.