A method of writing data in a storage device is provided. The method includes: receiving an identifier information request; outputting information indicating a plurality of identifiers based on the identifier information request; receiving a first write command and first data, the first write command comprising a first identifier among the plurality of identifiers; performing a data write operation on the first data based on the first write command; receiving a first attribute assignment command comprising the first identifier and a first attribute among a plurality of attributes; and assigning the first attribute to the first data that is already stored in the storage device based on the first attribute assignment command.