OFFSET PROTECTION DATA IN A RAID ARRAY

• US 20120079190A1
• Filed: 09/28/2010
• Published: 03/29/2012
• 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
• Granted Patent: US 9,244,769 B2
• Time in Patent Office: Days
• 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 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

A system and method for offset protection data 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 store user data in a first page of a first storage device of the plurality of storage devices; generate intra-device protection data corresponding to the user data, and store the intra-device protection data at a first offset within the first page. The controller is further configured to generate inter-device protection data corresponding to the first page, and store the inter-device protection data at a second offset within a second page in a second storage device of the plurality of storage devices, wherein the first offset is different from the second offset.

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, wherein the subsystem comprises a plurality of data storage locations on a plurality of storage devices;

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

store user data in a first page of a first storage device of the plurality of storage devices;

generate intra-device protection data corresponding to the user data, and store the intra-device protection data at a first offset within the first page; and

generate inter-device protection data corresponding to the first page, and store the inter-device protection data at a second offset within a second page in a second storage device of the plurality of storage devices, wherein the first offset is different from the second offset.

2. The computer system as recited in claim 1, wherein the protection data in the first page is a checksum value computed from corresponding data stored in the first page of the first storage device.

3. The computer system as recited in claim 2, wherein the second storage device further stores intra-device protection data for the second page in the second storage device.

4. The computer system as recited in claim 1, wherein the first storage device is formatted to a multiple of 512 sector size such that the first page is aligned to a multiple of 512 boundary, and wherein the data in the first page is compressed in order to accommodate storage of the intra-device protection data within the first page.

5. The computer system as recited in claim 1, wherein the intra-device protection data in the first page further includes one or both of a physical address or a virtual address corresponding to the user data stored within the first page.

6. The computer system as recited in claim 5, wherein in response to a read of data in the first page, the storage controller is configured to utilize at least one of the physical address or the virtual address to validate the read data.

7. The computer system as recited in claim 1, wherein in response to a read of given data in the first page, the storage controller is configured to:

utilize intra-device protection data to attempt to rebuild the given data, in response to determining a checksum validation for the given data has failed; and

utilize inter-device protection data to reconstruct the given data, in response to determining the rebuild has failed.

8. The computer system as recited in claim 1, wherein said first page comprises one or more client blocks storing compressed data, and wherein the first page further includes additional protection data for each of the client blocks, the additional data being configured to validate corresponding data in an uncompressed state.

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

receiving read and write requests at a data storage subsystem, wherein the subsystem comprises a plurality of data storage locations on a plurality of storage devices;

storing user data in a first page of a first storage device of the plurality of storage devices;

generating intra-device protection data corresponding to the user data, and store the intra-device protection data at a first offset within the first page; and

generating inter-device protection data corresponding to the first page, and store the inter-device protection data at a second offset within a second page in a second storage device of the plurality of storage devices, wherein the first offset is different from the second offset.

10. The method as recited in claim 9, further comprising computing the protection data in the first page as a checksum value based on data stored in the first page of the first storage device.

11. The method as recited in claim 10, further comprising storing intra-device protection data for the second page in the second storage device.

12. The method as recited in claim 9, wherein the first storage device is formatted to a multiple of 512 sector size such that the first page is aligned to a multiple of 512 boundary, and wherein the method further comprises compressing the data in the first page in order to accommodate storage of the intra-device protection data within the first page.

13. The method as recited in claim 9, wherein the intra-device protection data in the first page further includes one or both of a physical address or a virtual address corresponding to the user data stored within the first page.

14. The method as recited in claim 13, wherein in response to a read of data in the first page, the method comprises utilizing at least one of the physical address or the virtual address to validate the read data.

15. The method as recited in claim 9, wherein in response to a read of given data in the first page, the method further comprises:

utilizing intra-device protection data to attempt to rebuild the given data, in response to determining a checksum validation for the given data has failed; and

utilizing inter-device protection data to reconstruct the given data, in response to determining the rebuild has failed.

16. The method as recited in claim 9, wherein said first page comprises one or more client blocks storing compressed data, and wherein the first page further includes additional protection data for each of the client blocks, the additional data being configured to validate corresponding data in an uncompressed state.

17. A computer readable storage medium storing program instructions, wherein the program instructions are executable to:

receive read and write requests at a data storage subsystem, wherein the subsystem comprises a plurality of data storage locations on a plurality of storage devices;

store user data in a first page of a first storage device of the plurality of storage devices;

generate intra-device protection data corresponding to the user data, and store the intra-device protection data at a first offset within the first page; and

generate inter-device protection data corresponding to the first page, and store the inter-device protection data at a second offset within a second page in a second storage device of the plurality of storage devices, wherein the first offset is different from the second offset.

18. The computer readable storage medium as recited in claim 17, wherein the program instructions are further executable to compute the protection data in the first page as a checksum value based on data stored in the first page of the first storage device.

19. The computer readable storage medium as recited in claim 18, wherein the program instructions are further executable to store intra-device protection data for the second page in the second storage device.

20. The computer readable storage medium as recited in claim 17, wherein the first storage device is formatted to a multiple of 512 sector size such that the first page is aligned to a multiple of 512 boundary, and wherein the wherein the program instructions are further executable to compress the data in the first page in order to accommodate storage of the intra-device protection data within the first page.

21. The computer readable storage medium as recited in claim 17, wherein the intra-device protection data in the first page further includes one or both of a physical address or a virtual address corresponding to the user data stored within the first page.

22. The computer readable storage medium as recited in claim 21, wherein in response to a read of data in the first page, the wherein the program instructions are further executable to utilize at least one of the physical address or the virtual address to validate the read data.