A technique for managing a data storage system that stores data in a set of RAID groups includes receiving IO requests specifying data to be written at different logical addresses and mapping the specified data to contiguous physical addresses, so as to produce contiguously-mapped data having a length equal to that of a full stripe of a RAID group. With data from the IO requests mapped to a contiguous, full-stripe range, the data storage system can write the data and its parity to a full stripe of the RAID group in a single set of operations.