Abstract: A destaging method for a mapped data storage system is provided for writing data to a backing store. Data having non-sequential logical addresses are grouped together. The data includes data segments. A maximal difference in size between two data segments is less than a predetermined value. A constructed data segment includes a particular data item when the particular data item has a logical address between logical addresses of two other data items when they are part of this same constructed data segment. After being grouped together, such data is destaged from a cache memory to the backing store. Data from a group is transferred to an unallocated storage area of the backing store nearest to the physical position of the data transfer head responsible for the transfer. Each such transfer is continuous while reducing seek and/or latency delays and without regard to the nonsequential logical addresses of the data being transferred.