Storage device having a non-volatile memory device and copy-back method thereof

A copy-back method of a storage device that includes a non-volatile memory device, the method comprising:

• reading data from a source page of the non-volatile memory device;
• performing an error correction code (ECC) decoding operation on each of a plurality of vectors in the read data, wherein among the plurality of vectors, a vector corresponding to a clean sector is determined as decoding pass without referring to any flag bit indicating a vector programming state among the plurality of vectors during the ECC decoding operation;
• and
• writing the decoded data via the ECC decoding operation into a target page of the non-volatile memory device.