Logically arranged hierarchy or tiered storage may comprise a layer of storage being a faster access storage (e.g. solid state drive (SSD)) and another (e.g., next) layer being a traditional disk (e.g. HDD). In one embodiment, compaction occurs within the higher layer, e.g., until there is no more room and then during the compaction sequence the data may be moved down to the lower layer. In another embodiment, compaction and migration to a lower layer may occur within the higher layer, e.g., based on one or more policies, even if the higher layer is not full. In one embodiment, the data between layers are maintained as disjoint. In one embodiment, the more recent versions are always in the higher layer and the older versions are always in the lower layer.