Memory system

A memory system comprising:

• a nonvolatile memory;
• a random access memory;
• and
• a controller configured to control the nonvolatile memory and the random access memory,
• wherein the controller is configured to:
• generate a first error correction code that constitutes an error correction code frame of a first size together with a data portion of a first unit to be written into the nonvolatile memory by encoding the data portion of the first unit, write the data portion of the first unit into the nonvolatile memory, and write the first error correction code into the nonvolatile memory or store the first error correction code in the random access memory;
• and
• when writing n−1 data portions of the first unit that are included in n−1 error correction code frames of the first size, respectively, in the nonvolatile memory, generate a second error correction code that constitutes an error correction code frame of a second size together with the n−1 data portions of the first unit and a second data portion to be written into the nonvolatile memory by encoding the n−1 data portions of the first unit and the second data portion, and write the second data portion and the second error correction code into the nonvolatile memory,
• wherein n is an integer greater than one.