A memory and storage device includes a data management system for transferring data units referenced by logical addresses. The data management system maps the logical addresses to sequential virtual addresses according to the order the data units are received. The data management system also maps the sequential virtual addresses to sequential physical addresses in a memory block of a memory device. Additionally, the data management system can modify a data unit in the memory block by copying any other valid data units in the memory block to another memory block and writing the modified data unit into this other memory block. The data management system writes the valid data units and the modified data unit into sequential physical addresses of this other memory block.