Storage device for reducing multi stream write imbalance and operation method thereof

A storage device comprising:

• a non-volatile memory device comprising a plurality of chips;
• and
• a storage controller configured to allocate a write-requested stream to at least one of the plurality of chips by referring to a program status and a stream queue state of each of the plurality of chips,
• wherein, based on a determination that at least one chip in a ready state with an empty stream queue exists among the plurality of chips, the storage controller is configured to allocate the write-requested stream to the at least one chip in the ready state, and
• wherein, based on a determination that there is no chip in the ready state with the empty stream queue among the plurality of chips, the storage controller is configured to allocate the write-requested stream to at least one chip based on a number of streams in a stream queue among the plurality of chips.

A method of operating a storage device comprising a plurality of NAND chips:

• receiving a write request for stream data;
• checking a word line offset indicating a programmed word line of each of the plurality of NAND chips;
• selecting candidate chips to write the stream data according to the word line offset;
• and
• programming the stream data into the candidate chips,
• wherein in the selecting the candidate chips, at least one chip having an unprogrammed first word line and at least one chip having an unprogrammed second word line to be programmed after the first word line are selected as the candidate chips among the plurality of NAND chips.