# US 2021/0278972 A1 · Storage device, storage system, and method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0278972 A1 - Document ID: US20210278972A1 - Status: Published application - Kind: A1 - Application number: 17/118,996 - Filed: 2020-12-11 - Published: 2021-09-09 - Earliest claimed: 2020-03-05 - Assignees: Kioxia Corporation - Applicants: Kioxia Corporation - Inventors: Takeshi ISHIHARA; Yohei HASEGAWA; Shinichi KANNO; Kohei OKUDA; Masataka GOTO - Web page: https://patentgrep.com/patent/US20210278972A1 ## CPC - G06F 3/0608: {Saving storage space on storage systems} - G06F 3/0644: {Management of space entities, e.g. partitions, extents, pools} - G06F 3/0616: {in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]} - G06F 3/0652: {Erasing, e.g. deleting, data cleaning, moving of data to a wastebasket} - G06F 3/0679: {Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]} - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract According to one embodiment, a storage device includes a non-volatile memory and a control unit that is electrically connected to the non-volatile memory and that is configured to control the non-volatile memory. The control unit is configured to manage a plurality of management areas obtained by logically partitioning storage area of the non-volatile memory, when a write request is received that includes data for which a valid term has been set, determine, based on the valid term, a first management area from among the management areas, write the data included in the write request to the determined first management area, and when the data written to the first management area is erased, collectively erase all data written in the first management area which includes the data. ## Claims ### Claim 1 A storage device, comprising: a non-volatile memory; and a control unit that is electrically connected to the non-volatile memory and that is configured to control the non-volatile memory, wherein the control unit is configured to: manage a plurality of management areas obtained by logically partitioning storage area of the non-volatile memory, when a write request is received that includes data for which a valid term has been set, determine, based on the valid term, a first management area from among the management areas, write the data included in the write request to the determined first management area, and when the data written to the first management area is erased, collectively erase all data written in the first management area which includes the data. ### Claim 2 (depends on 1) The storage device according to claim 1, wherein non-overlapping valid terms are respectively assigned to the management areas, and the control unit is configured to determine the first management area which has been assigned the valid term that includes an end time of the valid term set for the data included in the write request. ### Claim 3 (depends on 2) The storage device according to claim 2, wherein the plurality of areas include a first management area to which a first valid term is assigned, and a second management area to which a second valid term longer than the first valid term is assigned, and when the first valid term assigned to the first management area has elapsed, the second valid term assigned to the second management area is shortened based on the first valid term. ### Claim 4 (depends on 2) The storage device according to claim 2, wherein, when the valid term assigned to the first management area to which the data is written has elapsed, the control unit is configured to collectively erase all data written to the first management area. ### Claim 5 (depends on 1) The storage device according to claim 1, wherein the control unit is configured to write the data included in the write request to the first management area so as to be additionally written starting at the end of data which has already been written to the determined first management area. ### Claim 6 (depends on 5) The storage device according to claim 5, wherein, when free capacity of the determined first management area is inadequate, the control unit is configured to: write a portion of the data to the free capacity of the first management area, erase other data, which has been written at the beginning of the first management area, to secure capacity of a size enabling the other portion of the data to be written, and write the other portion of the data, starting at the beginning of the first management area. ### Claim 7 (depends on 2) The storage device according to claim 2, wherein, when free capacity of the determined first management area is inadequate, the control unit is configured to write the data to a second management area to which a valid term longer than the valid term which has been set for the data is assigned. ### Claim 8 (depends on 7) The storage device according to claim 7, wherein the control unit is configured to determine, within the second management area to which a valid term longer than the valid term set for the data is assigned, the second management area to which the data is written, based on at least one of the valid term assigned to the second management area, the free capacity of the second management area, and the write frequency and read frequency to/from the second management area. ### Claim 9 (depends on 2) The storage device according to claim 2, wherein, when free capacity of the determined first management area is inadequate, the control unit is configured to write the data to a second management area to which the valid term is not assigned. ### Claim 10 (depends on 1) The storage device according to claim 1, wherein the determined first management area includes storage area of each of a plurality of non-volatile memories having different characteristics, and the control unit is configured to determine a non-volatile memory to which the data included in the write request is to be written, based on the valid term which has been set for the data, and the characteristics of each of the non-volatile memories. ### Claim 11 A storage system, comprising: a storage device comprising a non-volatile memory; and a control unit that is electrically connected to the storage device and that is configured to control the non-volatile memory, wherein the control unit is configured to: manage a plurality of management areas obtained by logically partitioning storage area of the non-volatile memory provided to the storage device, when a write request is received that includes data for which a valid term has been set, determine, based on the valid term, a first management area from among the management areas, write the data included in the write request to the determined first management area, and when the data written to the first management area is erased, collectively erase all data written in the first management area which includes the data. ### Claim 12 A method, comprising: managing a plurality of management areas obtained by logically partitioning storage area of a non-volatile memory; when a write request is received that includes data for which a valid term has been set, determining, based on the valid term, a first management area from among the management areas; writing the data included in the write request to the determined first management area; and when the data written to the first management area is erased, collectively erasing all data written in the first management area which includes the data.