MEMORY SYSTEM WITH VARIABLE LENGTH PAGE STRIPES INCLUDING DATA PROTECTION INFORMATION

• US 20150378819A1
• Filed: 09/07/2015
• Published: 12/31/2015
• Est. Priority Date: 08/11/2009
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Frost, Holloway H., Camp, Charles J., Fuxa, James A.
• Granted Patent: US 9,983,927 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1016 Error in accessing a memory location, i.e. addressing error
• CPC Class Codes: G06F 11/1044 with specific ECC/EDC distribution
• CPC Class Codes: G06F 11/1068 in sector programmable memories, e.g. flash disk G06F11/1072 takes precedence
• 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 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/14 Protection against unauthorised use of memory or access to memory
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0644 Management of space entities, e.g. partitions, extents, pools
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G11C 29/52 Protection of memory contents; Detection of errors in memory contents

Abstract

Methods and apparatuses for enhanced protection of data stored in a non-volatile memory system involve a controller capable of adapting to the failure of one or more non-volatile memory devices in the memory system. The controller stores data in the form of page stripes, each page stripe composed of data pages, and each data page stored in a different non-volatile memory device. The controller also detects failure of a non-volatile memory device in which a data page of a particular page stripe is stored, reconstructs the data page, and stores the reconstructed data page in a new page stripe, where the number of data pages in the new page stripe is less than the number of data pages in the particular page stripe, and where no page of the new page stripe is stored in a memory location within the failed non-volatile memory device.

Claims

1. A non-volatile memory based solid state storage system comprising:

a printed circuit board;

a plurality of non-volatile memory chips mounted to the printed circuit board, each non-volatile memory chip divided into planes, each plane divided into blocks, each block divided into pages, and each page including a plurality of non-volatile memory cells arranged to store a page of digital data, each non-volatile memory chip including a chip-level communications bus interface capable of receiving and sending digital data to be stored in, and retrieved from, non-volatile memory cells within the non-volatile memory chip; and

a system controller mounted to the printed circuit board, the system controller including a plurality of system communication bus interfaces, each system communication bus interface being coupled by a system communications bus to one or more chip-level communication bus interfaces such that the system controller can provide digital data to and retrieve digital data from memory cells within the one or more non-volatile memory chips, the system controller further including an external communications bus interface capable of receiving digital data to be stored within the storage system;

wherein the system controller is configured to store data received over the external communications bus in the plurality of non-volatile memory chips in the form of page stripes, each page stripe comprising a plurality of pages stored in the non-volatile memory chips, each of the plurality of pages being stored in a non-volatile memory chip that is different from, but in the same plane and block as, each of the non-volatile memory chips in which the other pages within the page stripe are stored, the plurality of pages making up each page stripe including;

a plurality of data pages, and

at least one data protection page containing data protection information that may be used to reconstruct data stored in a data page within the page stripe that becomes corrupted or unavailable, the data protection information for a given page stripe being obtained by performing a bitwise logical operation on the information within the data pages for the given page stripe;

the page stripes stored by the system controller including;

a first page stripe stored within the plurality of non-volatile memory chips, the first page stripe having N data pages and one data protection page, where N is an integer greater than three; and

a second page stripe stored within the plurality of non-volatile memory chips, the second page stripe having M data pages and one data protection page, where M is an integer less than N, wherein each of the data pages within the second page stripe is stored within a non-volatile memory chip and a plane that also store data from a data page within the first page stripe.

2. The non-volatile memory based solid state storage system of claim 1 wherein the system controller is a field programmable gate array (FPGA).

3. The non-volatile memory based solid state storage system of claim 1 wherein the bitwise logical operation used to obtain the data protection information for each page stripe is an exclusive-or (XOR) operation.

4. The non-volatile memory based solid state storage system of claim 3 further comprising circuitry for generating the data protection information for each page stripe by performing XOR operations on data from the data pages within the page stripe.

5. The non-volatile memory based solid state storage system of claim 1 wherein N is nine.

6. The non-volatile memory based solid state storage system of claim 1 wherein the system controller is configured such that each data page includes error correction code data, the error correction code data being generated by the system controller using data within the page that was initially received over the external communication bus.

7. The non-volatile memory based solid state storage system of claim 6 wherein the system controller is configured to use the error correction code data within each data page to identify information within a given page that is corrupted or unavailable.

8. A board-mounted non-volatile-based memory storage system comprising:

a printed circuit board;

a plurality of non-volatile memory devices, each mounted to the printed circuit board and divided into planes, each plane divided into blocks, each block divided into pages, each page including a plurality of non-volatile memory cells arranged to store a page of data;

a controller mounted to the printed circuit board; and

a plurality of communications buses, each configured to allow the controller to write a data collection to one or more non-volatile memory devices;

wherein the controller is configured to write data to the non-volatile memory devices in a striped fashion using data stripes, where each data stripe includes a group of data collections and an associated set of data protection information such that;

each data collection within a group of data collections is written into a non-volatile memory device that differs from, but in the same plane and block as;

the non-volatile memory devices into which the other data collections within the group of data collections are written; and

the non-volatile memory device to which the data protection information associated with the group of data collections is written;

each data collection includes error correction code data generated from the data stored in the data collection; and

each set of data protection information is generated by performing a bitwise exclusive-or (XOR) of the data within the data collections associated with the set of data protection information;

wherein the controller is adapted to use the error correction code data within each data collection to identify an error within the data collection;

wherein the controller further includes circuitry for using the set of data protection information to reconstruct the data for a data collection associated with the set of data protection information; and

wherein the controller is configured such that the number of data collections within the group of data collections can vary.

9. The board-mounted non-volatile-based memory storage system of claim 8 where the number of bits in each data collection is equal to the number of bits in each set of data protection information.

10. The board-mounted non-volatile-based memory storage system of claim 8 wherein the controller is a field programmable gate array including circuitry for calculating the bitwise XOR of a plurality of data collections within a group of data collections.

11. The board-mounted non-volatile-based memory storage system of claim 8 further including a first group of M data collections stored in the plurality of non-volatile memory devices and a second group of N data collections stored in the plurality of non-volatile memory devices, where M is an integer number greater than three and where N is less than M.

12. The board-mounted non-volatile memory storage system of claim 11 wherein there are O non-volatile memory devices, where O is an integer greater than M.

13. The board-mounted non-volatile-based memory storage system of claim 12 wherein the number of communications buses is equal to O divided by two.

14. The board-mounted non-volatile-based memory storage system of claim 8 wherein each of the plurality of non-volatile memory devices is a non-volatile memory chip, and wherein each non-volatile memory chip is surface mounted to the printed circuit board.

15. A memory system comprising:

a plurality of non-volatile memory chips, each of the plurality of non-volatile memory chips capable of storing a predefined number of bits of information and divided into planes, each plane divided into blocks, each block divided into pages, each page including a plurality of non-volatile memory cells arranged to store a page of data;

a system controller coupled to the non-volatile memory chips, wherein the system controller writes information to the non-volatile memory chips using data stripes;

a first data stripe stored in the plurality of non-volatile memory chips, the first data stripe including M data pages and a data protection page, where M is an integer greater than three and wherein information stored in the data protection page for the first data stripe was generated through the performance of a given operation on information stored within the M data pages of the first data stripe; and

a second data stripe stored in the plurality of non-volatile memory chips, the second data stripe including N data pages and a data protection page, where N is an integer less than M, and wherein information stored in the data protection page for the second data stripe was generated from the performance of the given operation on information stored within the N data pages of the second data stripe;

wherein each of the data pages within the second data stripe is stored within a non-volatile memory chip and plane that also store data from a data page within the first data stripe.

16. The memory system of claim 15 wherein the given operation is a bitwise exclusive-or (XOR) operation.

17. The memory system of claim 15 wherein each data page within the first data stripe is stored in a non-volatile chip that is different from the non-volatile chips in which the other data pages within the first data stripe are stored.

18. The memory system of claim 17 wherein each data page within the second data stripe is stored in a non-volatile memory chip that is different from the non-volatile memory chips in which the data pages within the second data stripe are stored.

19. The memory system of claim 15 wherein the number of bits of information stored in each data page of the first data stripe is the same and wherein the number of bits of information stored in each data page of the second data stripe is the same as the number of bits of information stored in each data page of the first data stripe.

20. The memory system of claim 19 wherein the number of bits of information stored in the data protection page for the first data stripe is the same as the number of bits of information stored in the data protection page for the second data stripe.