A method is provided for managing a memory device including a plurality of physical memory segments. A logical memory space is classified into a plurality of classifications based on usage specifications. The plurality of physical memory segments is allocated to corresponding logical addresses based on the plurality of classifications, and on usage statistics of the physical memory segments. A data structure is maintained recording translation between logical addresses in the logical memory space and physical addresses of the physical memory segments. The plurality of classifications includes a first classification and a second classification having different usage statistic requirements than the first classification. Logical addresses having the second classification can be redirected to physical segments allocated to logical addresses having the first classification, and the data structure can be updated to record redirected logical addresses. A free command can release a physical memory segment allocated for main memory use.