Intra-device data protection in a raid array

• US 8,832,373 B2
• Filed: 06/10/2013
• Issued: 09/09/2014
• Est. Priority Date: 09/28/2010
• Status: Active Grant

• Current Assignee: Pure Storage, Inc.
• Original Assignee: Pure Storage, Inc.
• Inventors: Colgrove, John, Hayes, John, Hong, Bo, Miller, Ethan
• Primary Examiner(s): CHOE, YONG J
• Application Number:
  US13/914,248
• Publication Number:
  US 20130346690A1
• Time in Patent Office: 456 Days
• Field of Search: 711/114, 711/E12.103, 709/217
• US Class Current: 711/114
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/3034 where the computing system component is a storage system, e.g. DASD based or network based digital input from or digital output to record carriers G06F3/06; digital recording or reproducing G11B20/18; for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097
• CPC Class Codes: G06F 11/3055 Monitoring arrangements for monitoring the status of the computing system or of the computing system component, e.g. monitoring if the computing system is on, off, available, not available error or fault processing without redundancy G06F11/0703; error detection or correction by redundancy in data representation G06F11/08; error detection or correction by redundancy in operation G06F11/14; error detection or correction by redundancy in hardware G06F11/16
• CPC Class Codes: G06F 2211/1057 Parity-multiple bits-RAID6, i.e. RAID 6 implementations
• CPC Class Codes: G06F 2211/1059 Parity-single bit-RAID5, i.e. RAID 5 implementations
• CPC Class Codes: G06F 3/0605 by facilitating the interaction with a user or administrator
• CPC Class Codes: G06F 3/0614 Improving the reliability of storage systems
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0632 by initialisation or re-initialisation of storage systems
• CPC Class Codes: G06F 3/0653 Monitoring storage devices or systems
• CPC Class Codes: G06F 3/0655 Vertical data movement, i.e. input-output transfer; data movement between one or more hosts and one or more storage devices
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

A system and method for intra-device data protection in a RAID array. A computer system comprises client computers and data storage arrays coupled to one another via a network. A data storage array utilizes solid-state drives and Flash memory cells for data storage. A storage controller within a data storage array is configured to identify a unit of data stored in the data storage subsystem, wherein said unit of data is stored across at least a first storage device and a second storage device of the plurality of storage devices, each of the first storage device and the second storage device storing intra-device redundancy data corresponding to the unit of data; and change an amount of intra-device redundancy data corresponding to the unit of data on only the first storage device.

Claims

1. A computer system comprising:

a client computer configured to send read and write requests over a network;

a data storage subsystem coupled to the network configured to receive the read and write requests, the data storage subsystem comprising a plurality of storage devices;

wherein the data storage subsystem further comprises a storage controller configured to;

identify a unit of data stored in the data storage subsystem, wherein said unit of data is stored across at least a first storage device and a second storage device of the plurality of storage devices, each of the first storage device and the second storage device storing intra-device redundancy data corresponding to the unit of data; and

change an amount of intra-device redundancy data corresponding to the unit of data on only the first storage device without changing an amount of intra-device redundancy data corresponding to the unit of data on the second storage device.

2. The computer system as recited in claim 1, wherein said unit of data is a redundant array of independent drives (RAID) stripe, wherein the RAID stripe comprises user data and inter-device redundancy data, and wherein intra-device redundancy data in a given storage device is generated from user data and/or inter-device redundancy data contained only within the given storage device, and wherein the intra-device redundancy data is stored on the given storage device, and wherein the inter-device redundancy data is generated from data stored on other storage devices.

3. The computer system as recited in claim 1, wherein the storage controller is configured to:

store data indicative of characteristics of the plurality of storage devices; and

change an amount of intra-device redundancy data stored on the first storage device when writing a redundant array of independent drives (RAID) stripe in response to detecting an indication of a change in reliability of the first storage device, wherein said change in reliability is based at least in part on the characteristics.

4. The computer system as recited in claim 3, wherein the first storage device stores inter-device redundancy data for the unit of data, and wherein the storage controller is configured to reduce an amount of inter-device redundancy data stored on the first storage device for the unit of data responsive to increasing an amount of intra-device redundancy data corresponding to the unit of data stored on the first storage device.

5. The computer system as recited in claim 1, wherein the storage controller is configured to change said amount of intra-device redundancy data stored on the first storage device in response to detecting a characteristic of the first storage device, the characteristic being one or more of an error rate, an access rate, an age, an occupancy level, an expected life of data, and an age of stored data.

6. The computer system as recited in claim 1, wherein between two successive writes of two successive stripes among the plurality of storage devices, the storage controller is configured to determine for at least two different storage devices of the plurality of storage devices new distinct values for respective amounts of storage space for user data and corresponding intra-device redundancy data.

7. The computer system as recited in claim 1, wherein for a given unit of data stored across multiple storage devices of the plurality of storage devices, the storage controller is further configured to determine to utilize different amounts of intra-device redundancy data for at least two storage devices.

8. The computer system as recited in claim 1, wherein each of the first storage device and the second storage device further include a checksum for stored user data of the unit of data, and wherein in response to a read to at least a portion of the unit of data the storage controller is configured to:

utilize the checksum to validate corresponding read data; and

utilize intra-device redundancy data to rebuild the corresponding read data in response to detecting the checksum indicates the read data is not valid.

9. A method for use in a computing system, the method comprising:

receiving read and write requests at a data storage subsystem, the data storage subsystem comprising a plurality of storage devices;

identifying a unit of data stored in the data storage subsystem, wherein said unit of data is stored across at least a first storage device and a second storage device of the plurality of storage devices, each of the first storage device and the second storage device storing intra-device redundancy data corresponding to the unit of data; and

changing an amount of intra-device redundancy data corresponding to the unit of data on only the first storage device without changing an amount of intra-device redundancy data corresponding to the unit of data on the second storage device.

10. The method as recited in claim 9, wherein said unit of data is a redundant array of independent drives (RAID) stripe, wherein the RAID stripe comprises user data and inter-device redundancy data, and wherein intra-device redundancy data in a given storage device is generated from user data and/or inter-device redundancy data contained only within the given storage device, and wherein the intra-device redundancy data is stored on the given storage device, and wherein the inter-device redundancy data is generated from data stored on other storage devices.

11. The method as recited in claim 10, wherein for a given unit of data stored across multiple storage devices of the plurality of storage devices, the method further comprises determining to utilize different amounts of intra-device redundancy data for at least two storage devices.

12. The method as recited in claim 9, further comprising:

store data indicative of characteristics of the plurality of storage devices; and

changing an amount of intra-device redundancy data stored on the first storage device when writing a redundant array of independent drives (RAID) stripe in response to detecting an indication of a change in reliability of the first storage device, wherein said change in reliability is based at least in part on the characteristics.

13. The method as recited in claim 12, wherein the first storage device stores inter-device redundancy data for the unit of data, wherein the method further comprising reducing an amount of inter-device redundancy data stored on the first storage device for the unit of data responsive to increasing the amount of intra-device redundancy data corresponding to the unit of data stored on the first storage device.

14. The method as recited in claim 9, further comprising changing said amount of intra-device redundancy data stored on the first storage device in response to detecting a characteristic of the first storage device, the characteristic being one or more of an error rate, an access rate, an age, an occupancy level, an expected life of data, and an age of stored data.

15. The method as recited in claim 9, wherein between two successive writes of two successive stripes among the plurality of storage devices, the method comprises determining for at least two different storage devices of the plurality of storage devices new distinct values for respective amounts of storage space for user data and corresponding intra-device redundancy data.

16. The method as recited in claim 9, wherein each of the first storage device and the second storage device further include a checksum for stored user data of the unit of data, and wherein in response to a read to at least a portion of the unit of data the method further comprises:

utilizing the checksum to validate corresponding read data; and

utilizing intra-device redundancy data to rebuild the corresponding read data in response to detecting the checksum indicates the read data is not valid.

17. A non-transitory computer readable storage medium storing program instructions, wherein said program instructions are executable to:

receive read and write requests at a data storage subsystem, the data storage subsystem comprising a plurality of storage devices;

identify a unit of data stored in the data storage subsystem, wherein said unit of data is stored across at least a first storage device and a second storage device of the plurality of storage devices, each of the first storage device and the second storage device storing intra-device redundancy data corresponding to the unit of data; and

change an amount of intra-device redundancy data corresponding to the unit of data on only the first storage device without changing an amount of intra-device redundancy data corresponding to the unit of data on the second storage device.

18. The non-transitory computer readable storage medium as recited in claim 17, wherein said unit of data is a redundant array of independent drives (RAID) stripe, wherein the RAID stripe comprises user data and inter-device redundancy data, and wherein intra-device redundancy data in a given storage device is generated from user data and/or inter-device redundancy data contained only within the given storage device, and wherein the intra-device redundancy data is stored on the given storage device, and wherein the inter-device redundancy data is generated from data stored on other storage devices.

19. The non-transitory computer readable storage medium as recited in claim 17, wherein said program instructions are further executable to:

store data indicative of characteristics of the plurality of storage devices; and

change said amount of intra-device redundancy data stored on the first storage device in response to detecting an indication of a change in reliability of the first storage device, wherein said change in reliability is based at least in part on the characteristics.

20. The non-transitory computer readable storage medium as recited in claim 19, wherein the first storage device stores inter-device redundancy data for the unit of data, and wherein said program instructions are further executable to reduce an amount of inter-device redundancy data stored on the first storage device for the unit of data responsive to increasing the amount of intra-device redundancy data corresponding to the unit of data stored on the first storage device.