Techniques for providing data redundancy after reducing memory writes

• US 8,504,783 B2
• Filed: 03/07/2011
• Issued: 08/06/2013
• Est. Priority Date: 12/08/2006
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: LSI Corporation (Broadcom, Inc.)
• Inventors: Danilak, Radoslav
• Primary Examiner(s): NGUYEN, HIEP T
• Application Number:
  US13/042,252
• Publication Number:
  US 20120060002A1
• Time in Patent Office: 883 Days
• Field of Search: None
• US Class Current: 711/154
• CPC Class Codes: G06F 11/1072 in multilevel memories
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/108 Parity data distribution in semiconductor storages, e.g. in SSD
• CPC Class Codes: G06F 12/00 Accessing, addressing or allocating within memory systems or architectures digital input from, or digital output to record carriers, e.g. to disk storage units, G06F3/06
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 13/1668 Details of memory controller
• CPC Class Codes: G06F 2211/1073 Problems due to wear-out failures in RAID systems
• CPC Class Codes: G06F 2211/1092 Single disk raid, i.e. RAID with parity on a single disk
• CPC Class Codes: G06F 2211/1095 Writes number reduction, i.e. reducing the number of writes in a RAID array with parity
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0661 Format or protocol conversion arrangements
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• CPC Class Codes: G11C 29/52 Protection of memory contents; Detection of errors in memory contents

Abstract

A storage subsystem receives writes from a computer via a standard storage subsystem interface. The storage subsystem reduces a number of the writes. A single drive of the storage subsystem has primary and redundant storage devices with storage device interfaces. A disk controller of the single drive implements a data redundancy scheme by storing data associated with the reduced number of writes in the primary storage devices and by storing computed redundancy information in the redundant storage devices. The disk controller is operable without a loss of data in the presence of at least a single failure of any of the storage devices. Optionally the storage devices are flash memory devices. Optionally the disk controller is operable without a loss of data in the presence of at least two failures of any of the storage devices when a number of the redundant storage devices is at least two.

Claims

1. A method comprising:

receiving and reducing a number of writes from a computer via a standard storage subsystem interface;

in a single drive comprising one or more primary storage devices and one or more redundant storage devices, the storage devices having storage device interfaces, implementing, at least in part via a disk controller, a data redundancy scheme comprising storing data associated with the reduced number of writes in the primary storage devices and storing computed redundancy information in the redundant storage devices; and

wherein the disk controller is enabled to operate without a loss of data in the presence of at least a single failure of any of the storage devices.

2. The method of claim 1, wherein each of the redundant storage devices is a respective redundant flash memory device and each of the primary storage devices is a respective primary flash memory device.

3. The method of claim 1, wherein the data redundancy scheme includes a redundant array of independent disks (RAID)-5 data redundancy scheme.

4. The method of claim 1, wherein the disk controller is further enabled to operate without a loss of data in the presence of at least two failures of any of the storage devices when a number of the redundant storage devices is at least two.

5. The method of claim 4, wherein the data redundancy scheme includes a redundant array of independent disks (RAID)-6 data redundancy scheme.

6. The method of claim 1, wherein the standard storage subsystem interface comprises a SAS interface.

7. The method of claim 6, wherein the disk controller is included in the single drive.

8. The method of claim 7, wherein a printed circuit board includes the single drive.

9. The method of claim 2, wherein at least one of the flash memory devices comprises NAND flash memory.

10. The method of claim 9, wherein the NAND flash memory comprises single-level cell (SLC) NAND flash memory.

11. The method of claim 9, wherein the NAND flash memory comprises multi-level cell (MLC) NAND flash memory.

12. A non-transitory machine-readable storage medium having embodied therein a computer program product, comprising:

computer code for instructing a computer to execute writes to a storage subsystem via a standard storage subsystem interface;

computer code for providing, at least in part via the storage subsystem, a reducing of a number of the writes and a forwarding of the reduced number of writes to a single drive of the storage subsystem, the single drive having one or more primary storage devices and one or more redundant storage devices, the storage devices having storage device interfaces;

computer code for providing, at least in part via a disk controller of the storage subsystem, a data redundancy scheme comprising storing data associated with the reduced number of writes in the primary storage devices and storing computed redundancy information in the redundant storage devices; and

wherein the disk controller is enabled to operate without a loss of data in the presence of at least a single failure of any of the storage devices.

13. The non-transitory machine-readable storage medium of claim 12, wherein each of the redundant storage devices is a respective redundant flash memory device and each of the primary storage devices is a respective primary flash memory device.

14. The non-transitory machine-readable storage medium of claim 12, wherein the disk controller is further enabled to operate without a loss of data in the presence of at least two failures of any of the storage devices when a number of the redundant storage devices is at least two.

15. An apparatus comprising:

a circuit enabled to receive and reduce a number of writes from a computer via a standard storage subsystem interface;

a single drive comprising one or more primary storage devices, one or more redundant storage devices, and a disk controller;

wherein the storage devices have storage device interfaces, the single drive is enabled to implement, at least in part via the disk controller, a data redundancy scheme comprising storing data associated with the reduced number of writes in the primary storage devices and storing computed redundancy information in the redundant storage devices; and

wherein the disk controller is enabled to operate without a loss of data in the presence of at least a single failure of any of the storage devices.

16. The apparatus of claim 15, wherein each of the redundant storage devices is a respective redundant flash memory device and each of the primary storage devices is a respective primary flash memory device.

17. The apparatus of claim 16, wherein the data redundancy scheme includes a redundant array of independent disks (RAID)-5 data redundancy scheme.

18. The apparatus of claim 15, wherein the disk controller is further enabled to operate without a loss of data in the presence of at least two failures of any of the storage devices when a number of the redundant storage devices is at least two.

19. The apparatus of claim 18, wherein the data redundancy scheme includes a redundant array of independent disks (RAID)-6 data redundancy scheme.

20. The apparatus of claim 15, wherein the disk controller is included in the single drive and a printed circuit board includes the single drive.