Method to extend the lifespan of a data storage device by repurposing blocks from burst pool

Patent metadata

Field	Value
Publication number	US-12367138-B1
Application number	US-202418409550-A
Country	US
Kind code	B1
Filing date	Jan 10, 2024
Priority date	Jan 10, 2024
Publication date	Jul 22, 2025
Grant date	Jul 22, 2025

Abstract

A storage device postpones entry into a read-only mode due to faulty blocks that cannot be written to on a memory device. The memory device is divided into blocks. Blocks used for storing host data are placed in a main area pool, blocks used for storing host data and for peak write operations are placed in a burst pool, and blocks used for storing control information are placed in the control pool. A controller executes a read-only mode extension protocol to determine when a number of faulty blocks in the main area pool, control pool, or burst pool is approaching a threshold for placing the storage device in a read-only mode. If the storage device is approaching the read-only mode, the controller reduces and/or repurposes a number of the blocks used for storing host data in the burst pool to prevent the storage device from entering the read-only mode phase.

First claim

We claim:

1. A storage device postpones entry into a read-only mode due to faulty blocks that cannot be written to on a memory device, the storage device comprises:
a memory device divided into blocks, wherein blocks used for storing host data and covering a write capacity of the storage device are placed in a main area pool, blocks used for storing host data and for peak write operations are placed in a burst pool, and blocks used for storing control information are placed in a control pool; and
a controller to execute a read-only mode extension protocol, in response to determining when faulty blocks in one of the main area pool, the burst pool, and the control pool is approaching a threshold for placing the storage device in a read-only mode phase, at least one of reduce and repurpose a number of the blocks, used for storing host data in the burst pool, to prevent the storage device from entering the read-only mode phase.

2. The storage device of claim 1 , wherein the blocks in the burst pool are configured to store fewer bits per memory cell than the blocks in the main area pool.

3. The storage device of claim 1 , wherein the read-only mode extension protocol includes a first read-only mode extension protocol wherein when the controller determines i) that the storage device is entering the read-only mode phase because of a newly faulty block used for storing host data in the burst pool and ji) that the burst pool has a predefined minimum number of available blocks used for storing host data, the controller increases a bad block threshold of the burst pool by a preconfigured value and reduces the predefined minimum number of available blocks used for storing host data in the burst pool by the preconfigured value.

4. The storage device of claim 3 , wherein the controller determines the storage device is entering the read-only mode phase by comparing a number of bad blocks in the burst pool used for storing host data with the bad block threshold, wherein the bad block threshold represents a maximum allowable number of bad blocks in the burst pool.

5. The storage device of claim 1 , wherein the read-only mode extension protocol includes a second read-only mode extension protocol wherein when the controller determines i) that the storage device is entering the read-only mode phase because of a newly faulty block in the main area pool and ii) that the burst pool has a predefined minimum number of available blocks used for storing host data, the controller subtracts a predefined number of blocks used for storing host data from the burst pool, adds the subtracted predefined number of blocks to the main area pool, configures the subtracted predefined number of blocks added to the main area pool to a format storing more bits per memory cell, increases a bad block threshold of the main area pool by a preconfigured value, and reduces the burst pool by the predefined number of blocks subtracted from the burst pool.

6. The storage device of claim 5 , wherein the controller determines the storage device is entering the read-only mode phase by comparing a number of bad blocks in the main area pool with the bad block threshold, wherein the bad block threshold represents a maximum allowable number of bad blocks in the main area pool.

7. The storage device of claim 1 , wherein the read-only mode extension protocol includes a third read-only mode extension protocol wherein when the controller determines i) that the storage device is entering the read-only mode phase because of a newly faulty block in the control pool and ii) that the burst pool has a predefined minimum number of available blocks used for storing host data, the controller subtracts a predefined number of blocks used for storing host data from the burst pool, adds the subtracted predefined number of blocks to the control pool, configures the subtracted predefined number of blocks added to the control pool to store control data, increases a bad block threshold of the control pool by a preconfigured value, and reduces the burst pool by the predefined number of blocks subtracted from the burst pool.

8. The storage device of claim 7 , wherein the controller determines the storage device is entering the read-only mode phase by comparing a number of bad blocks in the control pool with the bad block threshold, wherein the bad block threshold represents a maximum allowable number of bad blocks in the control pool.

9. A method for delaying a storage device from entering into a read-only mode due to faulty blocks that cannot be written to on a memory device, the storage device comprises a controller to execute the method comprising:
storing host data in blocks in a main area pool on the memory device, storing host data for peak write operations in blocks in a burst pool on the memory device, and storing control information in blocks in a control pool on the memory device; and
executing a read-only mode extension protocol, in response to determining that faulty blocks in one of the main area pool, the burst pool, and the control pool is approaching a threshold for placing the storage device in a read-only mode phase, at least one of reducing and repurposing a number of the blocks, used for storing host data in the burst pool, to prevent the storage device from entering the read-only mode phase.

10. The method of claim 9 , wherein executing the read-only mode extension protocol comprises executing a first read-only mode extension protocol including:
determining i) that the storage device is entering the read-only mode phase because of a newly faulty block used for storing host data in the burst pool and ii) that the burst pool has a predefined minimum number of available blocks used for storing host data;
increasing a bad block threshold of the burst pool by a preconfigured value; and
reducing the predefined minimum number of available blocks used for storing host data in the burst pool by the preconfigured value.

11. The method of claim 10 , further comprising determining the storage device is entering the read-only mode phase by comparing a number of bad blocks in the burst pool with the bad block threshold, wherein the bad block threshold represents a maximum allowable number of bad blocks in the burst pool.

12. The method of claim 9 , wherein executing the read-only mode extension protocol comprises executing a second read-only mode extension protocol including:
determining i) that the storage device is entering the read-only mode phase because of a newly faulty block in the main area pool and ii) that the burst pool has a predefined minimum number of available blocks used for storing host data;
subtracting a predefined number of blocks used for storing host data from the burst pool;
adding the subtracted predefined number of blocks to the main area pool;
configuring the subtracted predefined number of blocks added to the main area pool to a format storing more bits per memory cell; and
increasing a bad block threshold of the main area pool by a preconfigured value and reducing the burst pool by the predefined number of blocks subtracted from the burst pool.

13. The method of claim 12 , further comprising determining the storage device is entering the read-only mode phase by comparing a number of bad blocks in the main area pool with the bad block threshold, wherein the bad block threshold represents a maximum allowable number of bad blocks in the main area pool.

14. The method of claim 9 , herein executing the read-only mode extension protocol comprises executing a third read-only mode extension protocol including:
determining i) that the storage device is entering the read-only mode phase because

Assignees

• Sandisk Technologies Llc
• Sandisk Technologies Inc

Inventors

• PATEL Karan
• Chopra Amit
• Jain Nitin

Classifications

• G06F2212/7204

  Capacity control, e.g. partitioning, end-of-life degradation · CPC title

• G06F12/0246 Primary

  in block erasable memory, e.g. flash memory · CPC title