Fast verification of non-volatile data integrity

A method of operating a non-volatile storage system, the method comprising:

• receiving a request at the non-volatile storage system from a host system to verify integrity of data stored in non-volatile memory cells in the storage system;
• determining a syndrome weight of one or more ECC codewords stored in the non-volatile memory cells in response to the request;
• responsive to the syndrome weight of each of the one or more ECC codewords being below a first threshold, reporting to the host system that the data to be verified meets a data integrity criterion;
• and
• performing the following for each respective ECC codeword of the data to be verified having a syndrome weight between the first threshold and a second threshold that is greater than the first threshold:
• decoding each respective ECC codeword;
• and
• based on a bit error rate of decoding each respective ECC codeword being below a third threshold that is between the first threshold and the second threshold, reporting to the host system that the data to be verified meets the data integrity criterion.

A non-volatile storage system comprising:

• non-volatile memory cells;
• sensing means for sensing multiple ECC codewords from the memory cells in response to a request to verify integrity of data stored in the memory cells;
• XOR means for forming an XOR codeword of the multiple ECC codewords;
• bit error rate means either for estimating or for determining whether a bit error rate of the XOR codeword is below a first threshold;
• and
• communication means for reporting that the data to be verified is likely to be decodable responsive to either the estimated bit error rate or the determined bit error rate of the XOR codeword being below the first threshold.