Data Integrity Enhancement to Protect Against Returning Old Versions of Data

• US 20160147468A1
• Filed: 02/24/2015
• Published: 05/26/2016
• Est. Priority Date: 11/21/2014
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Enterprise IP LLC (Western Digital Corporation)
• Inventors: Desai, Girish B., Guthrie, William L.
• Granted Patent: US 9,824,007 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/10 Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's
• CPC Class Codes: G06F 11/1004 to protect a block of data words, e.g. CRC or checksum G06F11/1076 takes precedence; security arrangements for protecting computers or computer systems against unauthorized activity G06F21/00
• CPC Class Codes: G06F 11/34 Recording or statistical evaluation of computer activity, e.g. of down time, of input/output operation ; Recording or statistical evaluation of user activity, e.g. usability assessment
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/1016 Performance improvement
• CPC Class Codes: G06F 2212/1036 Life time enhancement
• CPC Class Codes: G06F 2212/7201 Logical to physical mapping or translation of blocks or pages
• CPC Class Codes: G06F 2212/7205 Cleaning, compaction, garbage collection, erase control
• CPC Class Codes: G06F 2212/7207 management of metadata or control data
• CPC Class Codes: G06F 2212/7209 Validity control, e.g. using flags, time stamps or sequence numbers

Abstract

Systems, methods and/or devices are used to enable enhancing data integrity to protect against returning old versions of data. In one aspect, the method includes (1) receiving a write request from a host that specifies write data for a set of logical block addresses in a logical address space of the host, (2) mapping the set of logical block addresses to a set of physical addresses corresponding to physical pages of the storage device, and (3) performing one or more operations for each logical block specified by the set of logical block addresses, including: (a) generating metadata for the logical block, the metadata including a version number for the logical block, (b) storing the metadata, including the version number, in a header of a physical page in which the logical block is stored, and (c) storing the version number in a version data structure.

Claims

1. A method of enhancing data integrity, the method comprising:

receiving, at a storage device, a write request from a host, wherein the write request specifies write data for a first set of one or more logical block addresses in a logical address space of the host;

mapping, using a mapping table, the first set of one or more logical block addresses associated with the write request to a first set of one or more physical addresses of the storage device, the first set of one or more physical addresses corresponding to one or more physical pages of the storage device; and

performing one or more operations for each logical block specified by the first set of one or more logical block addresses, including;

generating metadata for the logical block, the metadata including a version number for the logical block;

storing the metadata, including the version number, for the logical block in a header of a physical page in which the logical block is stored; and

storing the version number for the logical block in a version data structure.

2. The method of claim 1, wherein performing one or more operations for each logical block specified by the first set of one or more logical block addresses further comprises:

in accordance with a determination that the logical block is modified;

obtaining an updated version number for the logical block;

mapping, using the mapping table, the logical block to a new physical page of the storage device;

storing the updated version number for the logical block in a header of the new physical page in which the logical block is stored; and

storing the updated version number for the logical block in the version data structure.

3. The method of claim 2, wherein obtaining an updated version number for the logical block comprises:

reading the version number for the logical block from the version data structure; and

incrementing the version number for the logical block.

4. The method of claim 1, further comprising:

receiving, at the storage device, a read request from the host, wherein the read request specifies a second set of one or more logical block addresses in the logical address space of the host from which to read;

mapping, using the mapping table, the second set of one or more logical block addresses associated with the read request to a second set of one or more physical addresses corresponding to one or more physical pages of the storage device; and

performing one or more operations for each logical block specified by the second set of one or more logical block addresses, including;

reading the version number for the logical block from the version data structure;

reading the version number for the logical block from the header of the physical page in which the logical block is stored;

comparing the version number from the version data structure with the version number from the header of the physical page; and

in accordance with a determination that the version number from the version data structure is not equivalent to the version number from the header of the physical page, initiating one or more recovery actions; and

in accordance with a determination that, for all the logical blocks specified by the second set of one or more logical block addresses, the version number from the version data structure is equivalent to the version number from the header of the physical page, returning data read from the second set of one or more logical block addresses to the host.

5. The method of claim 1, wherein the mapping table is stored independently from the version data structure.

6. The method of claim 1, wherein the metadata for the logical block includes a checksum from a Cyclic Redundancy Check (CRC) operation.

7. The method of claim 1, wherein the metadata for the logical block includes an identification value.

8. The method of claim 1, wherein the metadata for the logical block includes an application tag.

9. The method of claim 1, wherein the metadata for the logical block includes a reference tag.

10. The method of claim 1, wherein the storage device comprises one or more flash memory devices.

11. A storage device, comprising:

a storage medium;

memory distinct from the storage medium, the memory storing a mapping table, the mapping table including information for mapping logical addresses in a logic address space of a host to physical addresses in a physical address space of the storage system; and

a storage controller having one or more processors configured to execute instructions in one or more programs, wherein the storage controller is configured to perform operations comprising;

receiving, at the storage device, a write request from the host, wherein the write request specifies write data for a first set of one or more logical block addresses in the logical address space of the host;

mapping, using the mapping table, the first set of one or more logical block addresses associated with the write request to a first set of one or more physical addresses of the storage device, the first set of one or more physical addresses corresponding to one or more physical pages of the storage device; and

performing one or more operations for each logical block specified by the first set of one or more logical block addresses, including;

generating metadata for the logical block, the metadata including a version number for the logical block;

storing the metadata, including the version number, for the logical block in a header of a physical page in which the logical block is stored; and

storing the version number for the logical block in a version data structure.

12. The storage device of claim 11, wherein the storage controller includes a version module for generating the version number for the logical block and storing the version number for the logical block in the version data structure, and a recovery module for initiating one or more recovery actions in accordance with a determination that a version number obtained from the version data structure is not equivalent to a version number obtained from a header of a respective physical page in the storage medium.

13. The storage device of claim 11, wherein performing one or more operations for each logical block specified by the first set of one or more logical block addresses further comprises:

in accordance with a determination that the logical block is modified;

obtaining an updated version number for the logical block;

mapping, using the mapping table, the logical block to a new physical page of the storage device;

storing the updated version number for the logical block in a header of the new physical page in which the logical block is stored; and

storing the updated version number for the logical block in the version data structure.

14. The storage device of claim 12, wherein obtaining an updated version number for the logical block comprises:

reading the version number for the logical block from the version data structure; and

incrementing the version number for the logical block.

15. The storage device of claim 11, wherein the storage controller is further configured to perform operations comprising:

receiving, at the storage device, a read request from the host, wherein the read request specifies a second set of one or more logical block addresses in the logical address space of the host from which to read;

mapping, using the mapping table, the second set of one or more logical block addresses associated with the read request to a second set of one or more physical addresses corresponding to one or more physical pages of the storage device; and

performing one or more operations for each logical block specified by the second set of one or more logical block addresses, including;

reading the version number for the logical block from the version data structure;

reading the version number for the logical block from the header of the physical page in which the logical block is stored;

comparing the version number from the version data structure with the version number from the header of the physical page; and

in accordance with a determination that the version number from the version data structure is not equivalent to the version number from the header of the physical page, initiating one or more recovery actions; and

in accordance with a determination that, for all the logical blocks specified by the second set of one or more logical block addresses, the version number from the version data structure is equivalent to the version number from the header of the physical page, return data read from the second set of one or more logical block addresses to the host.

16. The storage device of claim 11, wherein the mapping table is stored independently from the version data structure.

17. The storage device of claim 11, wherein the metadata for the logical block includes a checksum from a Cyclic Redundancy Check (CRC) operation.

18. The storage device of claim 11, wherein the metadata for the logical block includes an identification value.

19. A non-transitory computer-readable storage medium, storing one or more programs configured for execution by one or more processors of a storage device, the one or more programs including instructions for:

receiving, at a storage device, a write request from a host, wherein the write request specifies write data for a first set of one or more logical block addresses in a logical address space of the host;

mapping, using a mapping table, the first set of one or more logical block addresses associated with the write request to a first set of one or more physical addresses of the storage device, the first set of one or more physical addresses corresponding to one or more physical pages of the storage device; and

performing one or more operations for each logical block specified by the first set of one or more logical block addresses, including;

generating metadata for the logical block, the metadata including a version number for the logical block;

storing the metadata, including the version number, for the logical block in a header of a physical page in which the logical block is stored; and

storing the version number for the logical block in a version data structure.

20. The storage medium of claim 19, wherein performing one or more operations for each logical block specified by the first set of one or more logical block addresses further comprises:

in accordance with a determination that the logical block is modified;

obtaining an updated version number for the logical block;

mapping, using the mapping table, the logical block to a new physical page of the storage device;

storing the updated version number for the logical block in a header of the new physical page in which the logical block is stored; and

storing the updated version number for the logical block in the version data structure.

21. The storage medium of claim 20, wherein obtaining an updated version number for the logical block comprises:

reading the version number for the logical block from the version data structure; and

incrementing the version number for the logical block.

22. The storage medium of claim 19, the one or more programs further comprising instructions for:

receiving, at the storage device, a read request from the host, wherein the read request specifies a second set of one or more logical block addresses in the logical address space of the host from which to read;

mapping, using the mapping table, the second set of one or more logical block addresses associated with the read request to a second set of one or more physical addresses corresponding to one or more physical pages of the storage device; and

performing one or more operations for each logical block specified by the second set of one or more logical block addresses, including;

reading the version number for the logical block from the version data structure;

reading the version number for the logical block from the header of the physical page in which the logical block is stored;

comparing the version number from the version data structure with the version number from the header of the physical page; and

in accordance with a determination that the version number from the version data structure is not equivalent to the version number from the header of the physical page, initiating one or more recovery actions; and

in accordance with a determination that, for all the logical blocks specified by the second set of one or more logical block addresses, the version number from the version data structure is equivalent to the version number from the header of the physical page, returning data read from the second set of one or more logical block addresses to the host.

23. The storage medium of claim 19, wherein the mapping table is stored independently from the version data structure.

24. The storage medium of claim 19, wherein the metadata for the logical block includes a checksum from a Cyclic Redundancy Check (CRC) operation.

25. The storage medium of claim 19, wherein the metadata for the logical block includes an identification value.