Metadata redundancy schemes for non-volatile memories

• US 9,342,449 B2
• Filed: 06/22/2015
• Issued: 05/17/2016
• Est. Priority Date: 09/18/2009
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Post, Daniel J., Khmelnitsky, Vadim, Wakrat, Nir Jacob
• Primary Examiner(s): SONG, HUA JASMINE
• Application Number:
  US14/745,994
• Publication Number:
  US 20150309928A1
• Time in Patent Office: 330 Days
• Field of Search: 711/103, 711/203, 711/162, 711/202, 711/E12.001, 711/E12.008
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1402 Saving, restoring, recovering or retrying
• CPC Class Codes: G06F 11/1666 where the redundant component is memory or memory area
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/7201 Logical to physical mapping or translation of blocks or pages
• CPC Class Codes: G06F 2212/7207 management of metadata or control data

Abstract

Systems and methods are provided for storing data to or reading data from a non-volatile memory (“NVM”), such as flash memory, using a metadata redundancy scheme. In some embodiments, an electronic device, which includes an NVM, may also include a memory interface for controlling access to the NVM. The memory interface may receive requests to write user data to the NVM. The user data from each request may be associated with metadata, such as a logical address, flags, or other data. In response to a write request, the NVM interface may store the user data and its associated metadata in a first memory location (e.g., page), and may store a redundant copy of the metadata in a second memory location. This way, even if the first memory location becomes inaccessible, the memory interface can still recover the metadata from the backup copy stored in the second memory location.

Claims

1. A method of storing data in a non-volatile memory, the method comprising:

receiving a first write request to write first user data to a first logical address;

receiving a second write request to write second user data to a second logical address;

identifying a second memory location at which to store the second user data;

programming the first user data and metadata in a first memory location of the non-volatile memory, wherein the metadata comprises;

first metadata associated with the first user data, and

second metadata associated with the second user data to be stored at the second memory location of the non-volatile memory;

programming the second user data and the second metadata at the second memory location.

2. The method of claim 1, wherein identifying the second memory location is based on a geometric relationship with respect to the first memory location.

3. The method of claim 2, wherein the first memory location is a previous page of a block and the second memory location is a current page of the same block.

4. The method of claim 2, wherein the first memory location is a page in a previous block and the second memory is page in a correspondingly similar position as the page of the previous block, but in a current block.

5. The method of claim 2, wherein the geometric relationship is a left-of-me redundancy scheme.

6. The method of claim 2, wherein the geometric relationship is an above-me redundancy scheme.

7. The method of claim 2, wherein the geometric relationship is a diagonal-of-me redundancy scheme.

8. The method of claim 1, wherein the first metadata comprises at least one of the first logical address, flags, and data associated with the first user data, and

the second metadata comprises a second logical address, flags, and data associated with the second user data.

9. The method of claim 1, wherein the second metadata further comprises third metadata associated with third user data stored at a third memory location of the non-volatile memory.

10. The method of claim 1, wherein the non-volatile memory comprises a flash memory, wherein the first memory location comprises a first page of the flash memory, and wherein the second memory location comprises a second page of the flash memory.

11. The method of claim 10, wherein the flash memory comprises a plurality of super blocks, wherein each of the super blocks comprises a sequence of blocks, wherein the first memory location and the second memory location are located in adjacent blocks of one of the super blocks, and wherein the first memory location and the second memory location correspond to pages having a same page number in their respective block.

12. The method of claim 10, wherein the flash memory comprises a plurality of blocks, wherein each of the blocks comprises a sequence of pages, and wherein the first memory location and the second memory location are located in adjacent pages of one block of the plurality of blocks.