Embodiments of the present disclosure relate to methods, devices and computer readable mediums for managing a storage system. The storage system includes a disk array which includes at least one disk array group. The method comprises in response to receiving a first message indicating that a failure occurs in a disk in the disk array, determining first information on a disk array group that the failed disk belongs to. The method further comprises obtaining a first number of outstanding input/output (I/O) operations on rebuilding the failed disk in the disk array group. The method further comprises determining, based on the first information and the first number, a threshold number of I/O operations that is applicable for the disk array group. In addition, the method further comprises controlling, based on the threshold number, the number of I/O operations initiated to the disk array group.