Techniques involve managing a storage space. In response to receiving an allocation request for allocating a storage space, a storage space size and a slice size are obtained. A first storage system and a second storage system are selected from multiple storage systems, the first storage system and the second storage system includes a first storage device group and a second storage device group respectively, and the first storage device group does not overlap the second storage device group. A first slice group and a second slice group is obtained from the first storage system and the second storage system respectively, on the basis of the size of the storage space and the size of the slice. A user storage system is built at least on the basis of the first slice group and the second slice group, so as to respond to the allocation request.