Error correction for storage devices

• US 8,988,800 B1
• Filed: 08/22/2014
• Issued: 03/24/2015
• Est. Priority Date: 09/15/2009
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Varnica, Nedeljko, Burd, Gregory, Tang, Heng
• Primary Examiner(s): Neyzari, Ali
• Application Number:
  US14/466,881
• Time in Patent Office: 214 Days
• Field of Search: 360/39, 360/51, 360/31, 360/53, 360/55, 360/78.04, 360/76, 360/48, 360/46, 360/65, 360/59, 711/114, 711/103, 711/154, 711/170, 711/167, 711/161, 711/104, 711/105
• US Class Current: 360/31
• CPC Class Codes: G06F 11/08 Error detection or correction by redundancy in data representation, e.g. by using checking codes
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G11B 20/1217 on discs
• CPC Class Codes: G11B 20/1833 by adding special lists or symbols to the coded information G11B20/1806, G11B20/1866 take precedence
• CPC Class Codes: G11B 2020/1222 ECC block, i.e. a block of error correction encoded symbols which includes all parity data needed for decoding pure error correction aspects G11B20/18
• CPC Class Codes: G11B 2020/1238 track, i.e. the entire a spirally or concentrically arranged path on which the recording marks are located

Abstract

Systems and techniques relating to storage devices, such as storage devices that employ Shingled Magnetic Recording (SMR), can include a device, which includes: circuitry configured to write stored data and parity data to discrete portions of a Shingled Magnetic Recording (SMR) track in a SMR storage device; and circuitry configured to recover stored data for one of the discrete portions of the SMR track using the parity data and the stored data read from remaining ones of the discrete portions of the SMR track.

Claims

1. A method comprising:

receiving, at a storage controller, a data request for a Shingled Magnetic Recording (SMR) storage device;

reading, in response to the data request, stored data and parity data from discrete portions of a SMR track in the SMR storage device;

detecting an error in data from the reading; and

recovering stored data for one of the discrete portions of the SMR track using the parity data and the stored data read from remaining ones of the discrete portions of the SMR track.

2. The method of claim 1, comprising using an error correcting code for data read from the discrete portions of the SMR track, wherein the recovering is performed for the one of the discrete portions of the SMR track when the error correcting code fails for the one of the discrete portions of the SMR track.

3. The method of claim 1, wherein the discrete portions of the SMR track are data sectors in the SMR storage device.

4. The method of claim 1, wherein the discrete portions of the SMR track compose the SMR track in its entirety.

5. The method of claim 1, wherein the discrete portions of the SMR track are a first section of the SMR track, the reading comprises reading the SMR track in its entirety, including additional stored data and additional parity data from one or more additional sections of the SMR track, and the method comprises recovering stored data for one or more of the one or more additional sections of the SMR track when an error correcting code fails for at least one discrete portion of the one or more additional sections of the SMR track.

6. The method of claim 1, wherein the SMR track is a first SMR track of the SMR storage device, and the method comprises initiating reading of a second SMR track, which is at a different location in the SMR storage device than the first SMR track, before completing the recovering for the first SMR track.

7. The method of claim 1, comprising:

writing the stored data and the parity data to the discrete portions of the SMR track in the SMR storage device before the reading;

accumulating an exclusive or'"'"'ed value in at least one parity buffer during both the writing and the reading; and

using memory protection with the at least one parity buffer.

8. The method of claim 1, comprising using an error correcting code and a cyclic redundancy check for data read from the discrete portions of the SMR track, wherein the recovering is performed for the one of the discrete portions of the SMR track when either the error correcting code or the cyclic redundancy check fails for the one of the discrete portions of the SMR track.

9. A device comprising:

circuitry configured to write stored data and parity data to discrete portions of a Shingled Magnetic Recording (SMR) track in a SMR storage device; and

circuitry configured to detect an error and recover stored data for one of the discrete portions of the SMR track using the parity data and the stored data read from remaining ones of the discrete portions of the SMR track.

10. The device of claim 9, wherein the circuitry configured to write comprises a track error correcting code (ECC) encoder, and the circuitry configured to detect an error and recover stored data comprises a track ECC decoder.

11. The device of claim 10, wherein the track ECC encoder comprises a track ECC parity buffer having a size equal to that of data sectors in the SMR storage device and configured to accumulate an exclusive or'"'"'ed value as the stored data is written to disk, and the track ECC decoder comprises a track ECC parity buffer having the size equal to that of data sectors in the SMR storage device and configured to accumulate an exclusive or'"'"'ed value as the stored data is read from disk.

12. The device of claim 11, comprising memory protection circuitry for the track ECC parity buffer for both the track ECC encoder and the track ECC decoder.

13. The device of claim 9, wherein the circuitry configured to write and the circuitry configured to recover are located in a read channel of the SMR storage device.

14. The device of claim 9, wherein the circuitry configured to write and the circuitry configured to recover are located in a hard disk controller for the SMR storage device, the hard disk controller being included on a system on chip.

15. A system comprising:

a Shingled Magnetic Recording (SMR) storage device; and

a storage controller coupled with the SMR storage device and configured to receive a data request for the SMR storage device, read stored data and parity data from discrete portions of a SMR track in the SMR storage device, and recover stored data for one of the discrete portions of the SMR track using the parity data and the stored data read from remaining ones of the discrete portions of the SMR track.

16. The system of claim 15, wherein the storage controller is configured to use an error correcting code for data read from the discrete portions of the SMR track, and recover the stored data for one of the discrete portions of the SMR track when the error correcting code fails for the one of the discrete portions of the SMR track.

17. The system of claim 15, wherein the discrete portions of the SMR track are data sectors in the SMR storage device.

18. The system of claim 17, wherein the storage controller is configured to recover stored data in respective groups of sectors in the SMR track in accordance with a user specified number of the groups of sectors.

19. The system of claim 17, wherein the SMR track is a first SMR track of the SMR storage device, and the storage controller is configured to initiate a read of a second SMR track, which is at a different location in the SMR storage device than the first SMR track, before completing a recovery for the first SMR track.

20. The system of claim 17, wherein the storage controller is configured to store track parity data for a partially completed write operation upon power-down.