A memory controller writes to a virtual address associated with data residing within an asymmetric memory component of main memory that is within a computer system and that has a symmetric memory component, while preserving proximate other data residing within the asymmetric memory component. The symmetric memory component within the main memory of the computer system is configured to enable random access write operations in which an address within a block of the symmetric memory component is written without affecting the availability of other addresses within the block of the symmetric memory component during the writing of that address. The asymmetric memory component is configured to enable block write operations in which writing to an address within a region of the asymmetric memory component affects the availability of other addresses within the region of the asymmetric memory component during the block write operations involving the address.