STORAGE DEVICE THAT WRITES DATA FROM A HOST DURING GARBAGE COLLECTION

• US 20180088805A1
• Filed: 02/23/2017
• Published: 03/29/2018
• Est. Priority Date: 09/23/2016
• Status: Active Grant

• Current Assignee: Kioxia Corporation
• Original Assignee: Toshiba Memory Corporation (Kioxia Corporation)
• Inventors: KANNO, Shinichi
• Granted Patent: US 10,761,733 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/0253 Garbage collection, i.e. reclamation of unreferenced memory
• CPC Class Codes: G06F 12/10 Address translation
• CPC Class Codes: G06F 2212/7201 Logical to physical mapping or translation of blocks or pages
• CPC Class Codes: G06F 2212/7204 Capacity control, e.g. partitioning, end-of-life degradation
• CPC Class Codes: G06F 2212/7205 Cleaning, compaction, garbage collection, erase control
• CPC Class Codes: G06F 2212/7206 Reconfiguration of flash memory system
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0656 Data buffering arrangements
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G06F 3/068 Hybrid storage device

Abstract

A memory system includes a controller, a buffer, and a nonvolatile memory including a plurality of blocks, wherein each of the blocks includes a plurality of pages and each of the pages includes a plurality of unit data portions. The controller is configured to carry out garbage collection by reading data from one or more pages of a target block of the garbage collection and selectively copying valid unit data portions included in the read data to another block, count a number of invalid unit data portions included in the read data, and accept, in the buffer, unit data portions from a host as write data, up to a number determined based on the counted number, during the garbage collection.

Claims

1. A storage device comprising:

a controller;

a buffer; and

a nonvolatile memory including a plurality of blocks, wherein each of the blocks includes a plurality of pages and each of the pages includes a plurality of unit data portions, wherein

the controller is configured to

carry out garbage collection by reading data from one or more pages of a target block of the garbage collection and selectively copying valid unit data portions included in the read data to another block,

count a number of invalid unit data portions included in the read data, and

accept, in the buffer, unit data portions from a host as write data, up to a number determined based on the counted number, during the garbage collection.

2. The storage device according to claim 1, wherein

the controller is further configured to write the accepted unit data portions in the buffer into a block in units of a page and decrement the counted number by a number of the unit data portions written into the block, during the garbage collection.

3. The storage device according to claim 1, wherein

the controller reads the data from the target block of the garbage collection until valid unit data portions included in the read data amount to one page, and then accept the unit data portions from the host up to the determined number.

4. The storage device according to claim 1, wherein

the controller is further configured to count a number of non-written portions in a block in which the data in the buffer is to be written, and accept, in the buffer, unit data portions from the host as write data, up to a number determined based on the counted number of non-written portions, while the garbage collection is not carried out.

5. The storage device according to claim 1, wherein

the controller is further configured to start the garbage collection upon determining that a number of free blocks in which no valid data are stored is less than a threshold.

6. The storage device according to claim 1, wherein

the controller is further configured to map the target block for the garbage collection as a free block in which no valid data are stored after valid unit data portions in all pages of the target block are copied.

7. The storage device according to claim 1, wherein

the controller is further configured to maintain an address mapping in units of the unit data portion.

8. The storage device according to claim 1, wherein

the controller is further configured to

associate one or more blocks of the nonvolatile memory and a first region of the buffer, with a first namespace such that data associated with the first namespace are selectively stored therein, and

associate other one or more blocks of the nonvolatile memory and a second region of the buffer, with a second namespace such that data associated with the second namespace are selectively stored therein, wherein

the garbage collection, the counting of the number, and the accepting of the write data from the host are carried out independently with respect to each of the first and second name spaces.

9. The storage device according to claim 1, wherein

the controller is further configured to

associate one or more blocks of the nonvolatile memory with a first namespace such that data associated with the first namespace are selectively stored therein, and

associate other one or more blocks of the nonvolatile memory with a second namespace such that data associated with the second namespace are selectively stored therein, wherein

the garbage collection and the counting of the number are carried out independently with respect to each of the first and second namespaces, and

unit data portions associated with the first namespace and unit data portions associated with the second namespace are accepted in the buffer, up to the determined number, which is determined based on a sum of the counted number for the first namespace and the counted number for the second namespace.

10. The storage device according to claim 9, wherein

the determined number is a quotient of the sum divided by a total number of free blocks in which no valid data are stored.

11. A method of operating a storage device including a buffer and a nonvolatile memory including a plurality of blocks, wherein each of the blocks includes a plurality of pages and each of the pages includes a plurality of unit data portions, the method comprising:

carrying out garbage collection by reading data from one or more pages of a target block of the garbage collection and selectively copying valid unit data portions included in the read data to another block;

counting a number of invalid unit data portions included in the read data; and

accepting, in the buffer, unit data portions from a host as write data, up to a number determined based on the counted number, during the garbage collection.

12. The method according to claim 11, further comprising:

writing the accepted unit data portions in the buffer into a block in units of a page, and decrementing the counted number by a number of the unit data portions written into the block, during the garbage collection.

13. The method according to claim 11, wherein

the data are from the target block of the garbage collection until valid unit data portions included in the read data amount to one page, and then the unit data portions from the host up to the determined number are accepted in the buffer.

14. The method according to claim 11, further comprising:

during a write operation during which the garbage collection is not carried out, counting a number of non-written portions in a block in which the data in the buffer is to be written, and accepting, in the buffer, unit data portions from the host as write data, up to a number determined based on the counted number of non-written portions.

15. The method according to claim 11, wherein

the garbage collection is started upon determining that a number of free blocks in which no valid data are stored is less than a threshold.

16. The method according to claim 11, further comprising:

mapping the target block for the garbage collection as a free block in which no valid data are stored after valid unit data portions in all pages of the target block are copied.

17. The method according to claim 11, further comprising:

maintaining an address mapping in units of the unit data portion.

18. The method according to claim 11, further comprising:

associating one or more blocks of the nonvolatile memory and a first region of the buffer, with a first namespace such that data associated with the first namespace are selectively stored therein; and

associating other one or more blocks of the nonvolatile memory and a second region of the buffer, with a second namespace such that data associated with the second namespace are selectively stored therein, wherein

the garbage collection, the counting of the number, and the accepting of the write data from the host are carried out independently with respect to each of the first and second name spaces.

19. The method according to claim 11, further comprising:

associating one or more blocks of the nonvolatile memory with a first namespace such that data associated with the first namespace are selectively stored therein; and

associating other one or more blocks of the nonvolatile memory with a second namespace such that data associated with the second namespace are selectively stored therein, wherein

the garbage collection and the counting of the number are carried out independently with respect to each of the first and second namespaces, and

unit data portions associated with the first namespace and unit data portions associated with the second namespace are accepted in the buffer, up to the determined number, which is determined based on a sum of the counted number for the first namespace and the counted number for the second namespace.

20. The method according to claim 19, wherein

the determined number is a quotient of the sum divided by a total number of free blocks in which no valid data are stored.