Abstract: A storage device includes a nonvolatile memory device, and a controller that receives a write command, data, and a signature associated with the data from an external device, generates a first hash value from the data, generates a second hash value from the signature, generates an output hash value based on the first hash value and the second hash, and detects whether the data received from the external device are previously written in the nonvolatile memory device, by using the output hash value.

Abstract: In a method of operating a SSD device, which includes a nonvolatile memory device having a plurality of memory blocks, the plurality of memory blocks is operated in a single level cell (SLC) mode, an access pattern for each of a plurality of data units stored in each of the plurality of memory blocks of the nonvolatile memory device is periodically analyzed, an operation mode of at least one of the plurality of memory blocks is switched to a multi level cell (MLC) mode based on the analysis result, and at least one of data units is moved to a memory block operating in the MLC mode based on the analysis result.