A controlling system is used in a storage system. The storage system includes a host and at least one storage device connected to the host in series. The controlling system includes a detecting unit and a partitioning unit. The detecting unit is operable to detect the number of the at least one storage device. The partitioning unit is operable to partition the at least one storage device and generate a partition table and at least one partition information table. The partition table records partition information of the at least one storage device. Each partition information table is stored in a corresponding storage device and records storage information of the corresponding storage device.