A method and computer program product for reclaiming space of a data storage memory of a data storage memory system, and a computer-implemented data storage memory system are provided. The method includes: determining heat metrics of data stored in the data storage memory; determining relocation metrics related to relocation of the data within the data storage memory; determining utility metrics of the data relating the heat metrics to the relocation metrics for the data; and making the data whose utility metric fails a utility metric threshold, available for space reclamation. Thus, data that otherwise may be evicted or demoted, but that meets or exceeds the utility metric threshold, is exempted from space reclamation and is instead maintained in the data storage memory.