A storage system may include a memory device including a first region including a single-level cell and a second region different from the first region, and a storage controller configured to read data from the first region at a first gear level of a plurality of gear levels, determine an error level of the read data and a state of the memory device, and change the first gear level to a second gear level of the plurality of gear levels based on the determined error level of the data and the determined state of the memory device.