Memory system and method

A memory system comprising:

• a nonvolatile memory configured to store a plurality of first data units, the plurality of first data units corresponding to a plurality of second data units that has executed a first process, the first process including first coding that generates first parity data based on the plurality of second data units, each of the plurality of second data units including first information;
• and
• a controller is configured to:
• execute a first operation, the first operation including reading the plurality of first data units from the nonvolatile memory and executing a second process on a plurality of third data units, the plurality of third data units corresponding to the read plurality of first data units, the second process including first decoding that performs error correction using the first parity data and the plurality of third data units,
• acquire second information from a fourth data unit, the second information corresponding to the first information of the fourth data unit, the fourth data unit being one of a plurality of fifth data units, the plurality of fifth data units corresponding to the plurality of third data units that has executed the first operation,
• compare third information that is an expected value of the second information, with the second information acquired from the fourth data unit, and
• re-execute the first operation when the third information and the second information are not equal.

A method for controlling a memory system, the memory system including a nonvolatile memory configured to store a plurality of first data units, the plurality of first data units corresponding to a plurality of second data units that has executed a first process, the first process including first coding that generates first parity data based on the plurality of second data units and first conversion executed after the first coding, each of the plurality of second data units including first information, the method comprising:

• reading the plurality of first data units from the nonvolatile memory;
• executing second conversion on a plurality of third data units, the second conversion being an inverse conversion of the first conversion, the plurality of third data units corresponding to the read plurality of first data units;
• executing first decoding using the first parity data and the plurality of third data units that has executed the second conversion;
• acquiring second information from a fourth data unit, the second information corresponding to the first information of the fourth data unit, the fourth data unit being one of a plurality of fifth data units, the plurality of fifth data units corresponding to the plurality of third data units that has executed the first decoding;
• comparing third information that is an expected value of the second information, with the second information acquired from the fourth data unit;
• and
• re-executing the reading the plurality of first data units, the executing the second conversion, and the executing the first decoding, when the third information and the second information are not equal.