Methods for phased garbage collection using phased garbage collection block or scratch pad block as a buffer

• US 20080086619A1
• Filed: 09/28/2006
• Published: 04/10/2008
• Est. Priority Date: 09/28/2006
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Corporation (Western Digital Corporation)
• Inventors: Traister, Shai, Lin, Jason
• Granted Patent: US 7,444,462 B2
• Time in Patent Office: Days
• US Class Current: 711/170
• CPC Class Codes: G06F 12/0269 Incremental or concurrent garbage collection, e.g. in real-time systems G06F12/0261 takes precedence

Abstract

A method for phased garbage collection is provided. In this method, a write command is received to write data. The write command is allocated a timeout period to complete an execution of the write command. Thereafter, a busy signal is asserted and a portion of a garbage collection operation is performed for a garbage collection time period. The data are written to a block and the busy signal is released before the timeout period.

Claims

1. A method for operating a memory system, comprising:

receiving a first write command to write a first plurality of data, the first write command being allocated a timeout period to complete an execution of the first write command;

asserting a busy signal;

copying a portion of a first plurality of valid data from one or more first blocks to a second block for a garbage collection time period;

writing the first plurality of data to a first phased garbage collection block; and

releasing the busy signal before the timeout period.

2. The method of claim 1, further comprising converting the first phased garbage block to an update block.

3. The method of claim 1, further comprising erasing the one or more first blocks.

4. The method of claim 1, wherein the one or more first blocks, the second block, and the third block are configured to span a single logical group.

5. The method of claim 1, wherein the copying the plurality of valid data from the one or more first blocks comprises:

tracking a time for the copying the portion of the plurality of valid data from the one or more first blocks to the second block; and

stopping the copying the portion of the plurality of valid data before the time exceeds the garbage collection time period.

6. The method of claim 1, wherein the first write command is a single sector write command.

7. The method of claim 1, wherein the garbage collection time period is a difference between the timeout period and a programming time associated with the writing the first plurality of data.

8. The method of claim 1, further comprising allocating a second phased garbage collection block configured to store a second plurality of data from a second write command, the second write command being received after the first write command.

9. A method for operating a memory system, comprising:

receiving a first write command to write a first plurality of data, the first write command being allocated a first timeout period to complete an execution of the first write command;

asserting a first busy signal;

copying a first portion of a plurality of valid data from one or more first blocks to a second block for a garbage collection time period;

writing the first plurality of data to a third block;

releasing the first busy signal before the first timeout period;

receiving a second write command to write a second plurality of data, the second write command being received after the receiving the first write command, the second write command being allocated a second timeout period to complete an execution of the second write command;

asserting a second busy signal;

copying a second portion of the plurality of valid data from the one or more first blocks to the second block for the garbage collection time period;

converting the third block to a first update block;

writing the second plurality of data to the first update block; and

releasing the second busy signal before the second timeout period.

10. The method of claim 9, further comprising erasing the one or more first blocks.

11. The method of claim 9, further comprising:

allocating a fourth block; and

writing the second plurality of data to the fourth block.

12. The method of claim 11, further comprising copying a plurality of valid data from one or more fifth blocks to a sixth block for a remaining garbage collection time period.

13. The method of claim 12, wherein the plurality of valid data are copied from the one or more fifth blocks to the sixth block within the second timeout period.

14. The method of claim 9, wherein the first and second write commands are single sector write commands.

15. A method for operating a memory system, comprising:

receiving a write command to write a plurality of data, the write command being allocated a timeout period to complete an execution of the write command;

asserting a busy signal;

copying a portion of a plurality of valid data from one or more first blocks to a second block for a garbage collection time period;

writing the plurality of data to a scratch pad block; and

releasing the busy signal before the timeout period.

16. The method of claim 15, wherein the write command is a single sector write command.

17. The method of claim 15, wherein the copying the portion of the plurality of valid data comprises:

tracking a time for the copying the portion of the plurality of valid data from the one or more first blocks to the second block; and

stopping the copying the portion of the plurality of valid data before the time exceeds the garbage collection time period.

18. The method of claim 15, wherein the garbage collection time period is a difference between the timeout period and a programming time associated with the writing the plurality of data.

19. A method for operating a memory system, comprising:

receiving a first write command to write a first plurality of data, the first write command being allocated a first timeout period to complete an execution of the first write command;

asserting a first busy signal;

copying a first portion of a plurality of valid data from one or more first blocks to a second block for a garbage collection time period;

writing the first plurality of data to a scratch pad block;

releasing the first busy signal before a timeout period;

receiving a second write command to write a second plurality of data, the second write command being received after the receiving the first write command, the second write command being allocated a second timeout period to complete an execution of the second write command;

asserting a second busy signal;

copying a second portion of the plurality of valid data from the one or more first blocks to the second block for the garbage collection time period; and

releasing the second busy signal before the second timeout period.

20. The method of claim 19, further comprising writing the second plurality of data to the scratch pad block.

21. The method of claim 19, further comprising writing the second plurality of data to an update block.

22. The method of claim 19, further comprising erasing the one or more first blocks after the copying the second portion of the plurality of valid data.

23. The method of claim 22, wherein the one or more first blocks are erased if the second portion of the plurality of valid data is a last portion of the plurality of valid data.

24. The method of claim 19, further comprising:

allocating an update block; and

copying the first plurality of data from the scratch pad block to the update block.

25. The method of claim 19, wherein the first and second write commands are single sector write commands.