Techniques change a type of a storage system. The techniques involve: determining, from a resource pool associated with the storage system, a set of used disks utilized by one stripe of the storage system and a set of spare disks unutilized by the stripe; determining a neighboring relationship between spare disks in the set of spare disks and used disks in the set of used disks, the neighboring relationship indicating a number of adjacencies between the spare disks and the used disks in a period of history time; selecting, based on the neighboring relationship, one spare disk from the set of spare disks as an expanded disk of the stripe; and updating the stripe of the storage system using extents of the expanded disk. Accordingly, the type of the storage system may be changed based on the existing resources to improve reliability and operating efficiency.