Storage subsystem capable of adjusting ECC settings based on monitored conditions

• US 8,296,625 B2
• Filed: 01/05/2012
• Issued: 10/23/2012
• Est. Priority Date: 09/06/2007
• Status: Active Grant

• Current Assignee: JP Morgan Chase Bank, N.A. (JP Morgan Chase & Co)
• Original Assignee: SiliconSystems, Inc. (Western Digital Corporation)
• Inventors: Diggs, Mark S., Merry, David E. Jr.
• Primary Examiner(s): Alphonse, Fritz
• Application Number:
  US13/344,502
• Publication Number:
  US 20120144270A1
• Time in Patent Office: 292 Days
• Field of Search: 714/763, 714/752, 714/710, 714/723, 714/54, 714/8, 711/171
• US Class Current: 714/762
• CPC Class Codes: G06F 11/1068 in sector programmable memories, e.g. flash disk G06F11/1072 takes precedence
• CPC Class Codes: G06F 2201/88 Monitoring involving counting

Abstract

A storage subsystem monitors one or more conditions related to the probability of a data error occurring. Based on the monitored condition or conditions, the storage subsystem adjusts an error correction setting, and thus the quantity of ECC data used to protect data received from a host system. To enable blocks of data to be properly checked when read from memory, the storage subsystem stores ECC metadata indicating the particular error correction setting used to store particular blocks of data. The storage subsystem may be in the form of a solid-state non-volatile memory card or drive that attaches to the host system.

Claims

1. A storage subsystem, comprising:

non-volatile storage;

a controller connected to the non-volatile storage and configured to write data to and read data from the non-volatile storage in response to instructions and data received from a host system; and

an error correction module configured to generate a quantity of error correction code (ECC) data corresponding to data that is to be written to the non-volatile storage;

wherein the controller selects the quantity of ECC data to be generated based at least in part on one or more monitored operating conditions of the storage subsystem; and

wherein the quantity of ECC data selected by the controller is generally proportional to a probability of data errors as determined at least in part by the one or more monitored operating conditions.

2. The storage subsystem of claim 1, wherein the controller selects the ECC setting based at least in part on one or more monitored operating conditions only when the storage subsystem is in an automatic mode.

3. The storage subsystem of claim 1, wherein the non-volatile storage comprises a flash memory device.

4. The storage subsystem of claim 1, wherein the non-volatile storage comprises a hard disk drive.

5. The storage subsystem of claim 1, wherein the error correction module is embedded in the controller.

6. The storage subsystem of claim 1, wherein the error correction module comprises a distinct device connected between the controller and the non-volatile storage.

7. The storage subsystem of claim 1, wherein the non-volatile storage comprises a user data area and a restricted data area, and wherein data indicating the monitored operating conditions of the storage subsystem is stored in the restricted data area.

8. The storage subsystem of claim 1, wherein the one or more monitored operating conditions comprise at least one type of monitored information selected from the group consisting of a duration of time for which the storage subsystem has been powered on, a power supply noise level, and a block erase count.

9. The storage subsystem of claim 1, wherein the one or more monitored operating conditions comprise at least one type of monitored information selected from the group consisting of a temperature of the storage subsystem, a wear level of the non-volatile memory, and a stability of a power signal received from the host system.

10. The storage subsystem of claim 1, further comprising a sensor selected from the group consisting of the following:

a temperature sensor, a humidity sensor, an altitude sensor, and an accelerometer;

wherein the sensor is configured to perform monitoring related to at least one of the one or more monitored operating conditions.

11. The storage subsystem of claim 1, wherein the error correction module is configured to generate error correction code data according to one of the following coding schemes:

Hamming code, BCH code, Reed-Solomon code, Reed-Muller code, Binary Golay code, convolutional code, and turbo code.

12. A method performed by a controller in a storage subsystem that comprises a non-volatile memory comprising a user data area that is accessible by a host system, the controller connected to the non-volatile memory and configured to receive instructions from the host system and to read data from and write data to the non-volatile memory according to the instructions, the method comprising:

receiving from the host system an instruction to write a block of data to the non-volatile memory;

determining a quantity of ECC data to be generated for the block of data based at least in part on monitor data indicating one or more monitored operating conditions of the storage subsystem that are associated with a probability of a data error, wherein the determined quantity of ECC data to be generated is generally proportional to a probability of a data error as determined at least in part by the monitor data;

generating the determined quantity of ECC data, the generated ECC data corresponding to the block of data;

storing the generated ECC data and data indicative of the determined quantity of ECC data; and

in response to receiving from the host system an instruction to read data stored in the non-volatile memory, accessing the stored ECC data and data indicative of the quantity of ECC data to detect data errors in data stored in the non-volatile memory.

13. The method of claim 12, further comprising correcting data errors in data stored in the non-volatile memory.

14. The method of claim 13, further comprising providing the corrected data to the host system.

15. The method of claim 12, wherein the one or more operating conditions comprise at least one of:

a temperature of the storage subsystem, a wear level of the non-volatile memory, and a stability of a power signal received from the host system.

16. The method of claim 12, wherein the storing comprises storing the generated ECC data and data indicative of the determined quantity of ECC data in a restricted area of the non-volatile memory.