A method includes: writing first data in a first partition of a first memory module and second data in a first partition of a second memory module, and selectively operating the first and second memory modules in a first operating mode and a second operating mode. The first operating mode includes writing parity bits for the first data in a second partition of the second memory module and parity bits for the second data in a second partition of the first memory module. The second operating mode includes writing further data instead of parity bits in the second partition of one or both the first memory module and the second memory module.