Methods, systems, and apparatuses related to runtime selection of memory devices and storage devices in a disaggregated memory system are described. For example, a controller can be coupled to a plurality of memory device and a plurality of storage devices. The controller can receive signaling indicative of a memory request corresponding to execution of an application. Responsive to receiving the signaling indicative of the memory request, the controller can select a memory device or a storage device, or both, selecting from the plurality of memory devices or the plurality of storage devices, or both, to perform a memory operation associated with the memory request. Responsive to receiving the memory request and selecting the memory device or the storage device, or both, the controller can perform the memory operation using the selected memory device or the selected storage device, or both.