A technique extends a storage system that includes a first storage resource pool that is generated using a first plurality of storage devices and based on a first storage array standard. Such a technique involves: adding a second plurality of storage devices to the storage system in response to receiving a request to extend the storage system, the number of the second plurality of storage devices being less than the sum of a first stripe width associated with the first storage array standard and the number of backup storage devices in the first storage resource pool; and creating a second storage resource pool using the second plurality of storage devices and based on a second storage array standard, a second stripe width associated with the second storage array standard being less than the first stripe width. Accordingly, storage space can be extended faster and more effectively.