Example implementations relate to storage space allocation. For example, an implementation includes an apparatus including a controller. The controller is to receive an allocation request from a host computing device. The controller is also to reserve a portion of storage space in the storage device via a reservation table based on the allocation request. The controller is further to determine a type of the allocation request. The type of the allocation request includes a space-optimized allocation request and a non-space-optimized allocation request. When the type of the allocation request corresponds to the non-space-optimized allocation request, the controller is to commit the portion of storage space via an allocation table. When the type of the allocation request corresponds to the space-optimized allocation request, the controller is to release the portion of storage space via the reservation table.