Memory system and control method

A memory system comprising:

• a nonvolatile memory that includes a plurality of access units;
• and
• a controller electrically connected to the nonvolatile memory and configured to:
• perform access to the nonvolatile memory for each access unit;
• manage a degree of wear-out of the nonvolatile memory for each wear management unit that includes P access units among the plurality of access units;
• and
• manage S addresses respectively indicating S access units accessed among the plurality of access units, wherein
• the controller is configured to, in a case where the S addresses include 2T addresses that are included in one wear management unit and are adjacent:
• manage (S−2T+1) addresses that include a compressed address and (S−2T) addresses, the compressed address representing the 2T addresses that are compressed, the (S−2T) addresses being obtained by excluding the 2T addresses from the S addresses;
• access a first access unit among the plurality of access units;
• make a first determination as to whether or not the S addresses include a first address indicative of the first access unit by using the (S−2T+1) addresses;
• and
• determine whether or not to increase a degree of wear-out of a first wear management unit that includes the first access unit, based on a result of the first determination,
• a bit length of each of the 2T addresses is same as a bit length of the compressed address,
• the compressed address includes T bits that are invalid in the first determination,
• P is an integer of two or more,
• S is an integer of two or more, and
• T is an integer of one or more.

A control method of a memory system that comprises a nonvolatile memory including a plurality of access units, the control method comprising:

• performing access to the nonvolatile memory for each access unit;
• managing a degree of wear-out of the nonvolatile memory for each wear management unit that includes P access units among the plurality of access units;
• managing Q pieces of first data that correspond to Q wear management units, respectively, the first data being data into which one or more addresses are converted, the one or more addresses respectively indicating one or more access units accessed among the P access units in each of the Q wear management units;
• accessing a first access unit among the P access units that are included in a first wear management unit among the Q wear management units;
• converting a first address indicative of the first access unit into second data;
• making a first determination as to whether there is a possibility that the first address is included in the one or more addresses converted into the first data corresponding to the first wear management unit among the managed Q pieces of first data by using the first data corresponding to the first wear management unit and the second data;
• and
• determining whether or not to increase a degree of wear-out of the first wear management unit, based on a result of the first determination, wherein
• a bit length of the first data is same as a bit length of the second data,
• P is an integer of two or more, and
• Q is an integer of one or more.