Data storage device extending erasures for LDPC-type decoding

A method of operating a data storage device, the method comprising:

• generating a plurality of codewords each comprising a plurality of symbols;
• generating a parity sector over the plurality of codewords;
• writing the plurality of codewords and the parity sector to a non-volatile storage medium (NVSM);
• reading the plurality of codewords and the parity sector from the NVSM;
• generating a reliability metric for each symbol of each codeword read from the NVSM;
• generating a number of erasures for a first codeword read from the NVSM, wherein the number of erasures exceeds the correction power of the first codeword;
• modifying a reliability metric of the first codeword corresponding to one of the erasures;
• first iteratively processing the reliability metrics for each codeword including the modified reliability metrics of the first codeword using a low density parity check (LDPC) type decoder, thereby first updating the reliability metric for each symbol of each codeword;
• second updating the reliability metrics for the first codeword using the parity sector;
• and
• second iteratively processing the second updated reliability metrics for the first codeword using the LDPC-type decoder.

Control circuitry configured to:

• generate a plurality of codewords each comprising a plurality of symbols;
• generate a parity sector over the plurality of codewords;
• write the plurality of codewords and the parity sector to a non-volatile storage medium (NVSM);
• read the plurality of codewords and the parity sector from the NVSM;
• generate a reliability metric for each symbol of each codeword read from the NVSM;
• generate a number of erasures for a first codeword read from the NVSM, wherein the number of erasures exceeds the correction power of the first codeword;
• modify a reliability metric of the first codeword corresponding to one of the erasures;
• first iteratively process the reliability metrics for each codeword including the modified reliability metrics of the first codeword using a low density parity check (LDPC) type decoder, thereby first updating the reliability metric for each symbol of each codeword;
• second update the reliability metrics for the first codeword using the parity sector;
• and
• second iteratively process the second updated reliability metrics for the first codeword using the LDPC-type decoder.