DATA BACKUP IN NON-VOLATILE MEMORY

• US 20020026566A1
• Filed: 02/05/1999
• Published: 02/28/2002
• Est. Priority Date: 06/08/1998
• Status: Abandoned Application

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: MIYAMOTO, NORIYUKI, HAMANO, NAMIO, YAMAHANA, SATORU, OOSAWA, TAKAKI, AWADA, KOSAKU, DEGUCHI, SATOMI, HANDA, TOSHIMITU
• Application Number:
  US09/245,809
• Publication Number:
  US 20020026566A1
• Time in Patent Office: Days
• US Class Current: 711/162
• CPC Class Codes: G06F 11/1456 Hardware arrangements for backup
• CPC Class Codes: G11C 16/102 External programming circuits, e.g. EPROM programmers; In-circuit programming or reprogramming; EPROM emulators
• CPC Class Codes: G11C 16/105 Circuits or methods for updating contents of nonvolatile memory, especially with 'security' features to ensure reliable replacement, i.e. preventing that old data is lost before new data is reliably written
• CPC Class Codes: G11C 16/349 Arrangements for evaluating degradation, retention or wearout, e.g. by counting erase cycles

Abstract

A method of storing data in a non-volatile memory medium which permits data writing in a memory area after old data thereof is erased is presented. The method includes the steps of providing a data-storage area in each of a plurality of non-volatile memories with respect to each of different data types, and writing incoming data of a given data type in a corresponding data-storage area in a first one of the non-volatile memories while a second one of the non-volatile memories is being subjected to data erasure of the given data type after a corresponding data-storage area in the second one of the non-volatile memories is filled with the incoming data of the given data type.

Claims

1. A method of storing data in a non-volatile memory medium which permits data writing in a memory area after old data thereof is erased, comprising the steps of:

a) providing a data-storage area in each of a plurality of non-volatile memories with respect to each of different data types; and

b) writing incoming data of a given data type in a corresponding data-storage area in a first one of the non-volatile memories while a second one of the non-volatile memories is being subjected to data erasure of the given data type after a corresponding data-storage area in the second one of the non-volatile memories is filled with the incoming data of the given data type.

2. The method as claimed in claim 1, wherein said step a) provides a plurality of sectors as the data-storage area in each of the plurality of non-volatile memories with respect to each of the different data types, wherein each of the plurality of non-volatile memories has data thereof erased by a unit of one sector.

3. The method as claimed in claim 1, further comprising a step of providing an evacuation buffer for each of the different data types, wherein said step b) comprises the steps of:

writing the incoming data of the given data type in a corresponding evacuation buffer and immediately transferring the incoming data from the corresponding evacuation buffer to the first one of the non-volatile memories when the first one of the non-volatile memories is available for data writing; and

continuing writing the incoming data of the given data type in the corresponding evacuation buffer when the first one of the non-volatile memories is being subjected to data erasure of a different data type, and transferring the incoming data from the corresponding evacuation buffer to the first one of the non-volatile memories when the first one of the non-volatile memories becomes available for data writing.

4. The method as claimed in claim 3, further comprising the steps of:

providing a replacement enabling unit in order to control a locked/unlocked condition of the non-volatile memories in terms of whether the non-volatile memories are locked in place; and

setting the replacement enabling unit to the locked condition when the evacuation buffer keeps therein data that has not been stored in the non-volatile memories.

5. The method as claimed in claim 2, further comprising a step of erasing used ones of the plurality of sectors in a given one of the non-volatile memories when writing the incoming data of the given data type in the plurality of sectors in the given one of the non-volatile memories if all the other ones of the non-volatile memories are in condition for needing replacement thereof.

6. The method as claimed in claim 2, further comprising a step of allocating another sector to the given data type when shortage of sectors is observed with regard to the plurality of sectors provided for the given data type.

7. A method of storing data in a non-volatile memory medium which permits data writing in a memory area after old data thereof is erased, comprising the steps of:

a) providing control-data areas for respective non-volatile memories in each of the non-volatile memories such that each of the control-data areas stores operation statuses of a corresponding one of the non-volatile memories; and

b) copying contents of a control-data area in a first one of the non-volatile memories to a control-data area in a second one of the non-volatile memories before erasing the control-data area in the first one of the non-volatile memories, thereby effecting continued control of the operation statuses of a corresponding one of the non-volatile memories.

8. The method as claimed in claim 7, wherein said step a) provides a plurality of sectors for the control areas in each of the non-volatile memories, wherein each of the non-volatile memories has data thereof erased by a unit of one sector.

9. The method as claimed in claim 8, further comprising a step of recording the operation statuses of a given one of the non-volatile memories in a corresponding control-data area with respect to each sector of the given one of the non-volatile memories.

10. The method as claimed in claim 8, further comprising the steps of:

c) writing operation statuses in the plurality of sectors in one of the non-volatile memories;

d) writing operation statuses in the plurality of sectors in another one of the non-volatile memories after using all the plurality of sectors in said one of the non-volatile memories, and erasing the plurality of sectors in said one of the non-volatile memories; and

repeating said steps c) and d) so as to effect recursive use of the plurality of sectors in the non-volatile memories.

11. The method as claimed in claim 8, further comprising a step of erasing used ones of the plurality of sectors in a given one of the non-volatile memories when writing operation statuses in the plurality of sectors in the given one of the non-volatile memories if all the other ones of the non-volatile memories are in condition for needing replacement thereof.

12. The method as claimed in claim 8, further comprising a step of allocating another sector to the control-data area when shortage of sectors is observed with regard to the plurality of sectors provided for the control-data area.

14. The method as claimed in claim 13, further comprising the steps of:

providing a plurality of memory areas functioning in the same manner as the memory area; and

moving from a first one of the memory areas to the second one of the memory areas when all the predetermined bits of the first one of the memory areas are changed for the counting of the number of occurrences of the given event, wherein remaining bits other than the predetermined bits are used for counting the number of occurrences of said moving based on a binary coded decimal, thereby counting the number of occurrences of the given event up to a number of the predetermined bits multiplied a number of the memory areas without a need for erasing the memory area.

16. The device as claimed in claim 15, wherein each of said non-volatile memories has a plurality of sectors provided as the data-storage area for each of the different data types, and has data thereof erased by a unit of one sector.

17. The device as claimed in claim 15, further comprising

an evacuation buffer provided for each of the different data types,

wherein said unit writes the incoming data of the given data type in a corresponding evacuation buffer to immediately transfer the incoming data from said corresponding evacuation buffer to the first one of said non-volatile memories when the first one of said non-volatile memories is available for data writing, and continues writing the incoming data of the given data type in said corresponding evacuation buffer when the first one of said non-volatile memories is being subjected to data erasure of a different data type, so as to transfer the incoming data from said corresponding evacuation buffer to the first one of said non-volatile memories when the first one of said non-volatile memories becomes available for data writing.

18. The device as claimed in claim 17, further comprising

a replacement enabling unit configured to control a locked/unlocked condition of said non-volatile memories in terms of whether said non-volatile memories are locked in place,

wherein said unit sets the replacement enabling unit to the locked condition when said evacuation buffer keeps therein data that has not been stored in said non-volatile memories.

19. The device as claimed in claim 16, wherein said unit erases used ones of the plurality of sectors in a given one of said non-volatile memories when writing the incoming data of the given data type in the plurality of sectors in the given one of said non-volatile memories if all the other ones of said non-volatile memories are in condition for needing replacement thereof.

20. The device as claimed in claim 16, wherein said unit allocates another sector to the given data type when shortage of sectors is observed with regard to the plurality of sectors provided for the given data type.

13. A method of storing data in a non-volatile memory medium which permits data writing in a memory area after old data thereof is erased, comprising the steps of:

providing a memory area which stores a number of occurrences of a given event in a non-volatile memory;

setting a first bit state in all bits of the memory area as initialization thereof; and

changing one of predetermined bits of the memory area from the first bit state to a second bit state each time the given event occurs, thereby counting the number of occurrences of the given event without a need for erasing the memory area.

15. A device for storing data in a non-volatile memory medium which permits data writing in a memory area after old data thereof is erased, comprising:

a plurality of non-volatile memories each having a data-storage area therein provided for each of different data types; and

a unit configured to write incoming data of a given data type in a corresponding data-storage area in a first one of said non-volatile memories while a second one of said non-volatile memories is being subjected to data erasure of the given data type after a corresponding data-storage area in the second one of said non-volatile memories is filled with the incoming data of the given data type.

21. A device for storing data in a non-volatile memory medium which permits data writing in a memory area after old data thereof is erased, comprising:

non-volatile memories each having therein control-data areas provided for the respective non-volatile memories such that each of the control-data areas stores operation statuses of a corresponding one of said non-volatile memories; and

a unit configured to copy contents of a control-data area in a first one of said non-volatile memories to a control-data area in a second one of said non-volatile memories before erasing the control-data area in the first one of said non-volatile memories, thereby effecting continued control of the operation statuses of a corresponding one of said non-volatile memories.

22. The device as claimed in claim 21, wherein each of said non-volatile memories has a plurality of sectors therein provided for the control areas, and has data thereof erased by a unit of one sector.

23. The device as claimed in claim 22, wherein said unit records the operation statuses of a given one of said non-volatile memories in a corresponding control-data area with respect to each sector of the given one of said non-volatile memories.

24. The device as claimed in claim 22, wherein said unit writes operation statuses in the plurality of sectors in one of said non-volatile memories, and writes operation statuses in the plurality of sectors in another one of said non-volatile memories after using all the plurality of sectors in said one of said non-volatile memories while erasing the plurality of sectors in said one of said non-volatile memories, thereby effecting recursive use of the plurality of sectors in said non-volatile memories.

25. The device as claimed in claim 22, wherein said unit erases used ones of the plurality of sectors in a given one of said non-volatile memories when writing operation statuses in the plurality of sectors in the given one of said non-volatile memories if all the other ones of said non-volatile memories are in condition for needing replacement thereof.

26. The device as claimed in claim 22, wherein said unit allocates another sector to the control-data area when shortage of sectors is observed with regard to the plurality of sectors provided for the control-data area.

28. The device as claimed in claim 27, wherein said non-volatile memory has a plurality of memory areas functioning in the same manner as the memory area, and wherein said unit switches a memory area for the counting from a first one of the memory areas to the second one of the memory areas when all the predetermined bits of the first one of the memory areas are changed from the first bit state to the second bit state, and uses remaining bits other than the predetermined bits for counting the number of occurrences of the switching of a memory area based on a binary coded decimal, thereby counting the number of occurrences of the given event up to a number of the predetermined bits multiplied a number of the memory areas without a need for erasing the memory area.

27. A device of storing data in a non-volatile memory medium which permits data writing in a memory area after old data thereof is erased, comprising:

a non-volatile memory having therein a memory area which stores a number of occurrences of a given event; and

a unit configured to set a first bit state in all bits of the memory area as initialization thereof, and to change one of predetermined bits of the memory area from the first bit state to a second bit state each time the given event occurs, thereby counting the number of occurrences of the given event without a need for erasing the memory area.

29. A device for storing data in a non-volatile memory medium which permits data writing in a memory area after old data thereof is erased, comprising:

a plurality of non-volatile memories each having a data-storage area therein provided for each of different data types; and

means for writing incoming data of a given data type in a corresponding data-storage area in a first one of said non-volatile memories while a second one of said non-volatile memories is being subjected to data erasure of the given data type after a corresponding data-storage area in the second one of said non-volatile memories is filled with the incoming data of the given data type.

30. A device for storing data in a non-volatile memory medium which permits data writing in a memory area after old data thereof is erased, comprising:

non-volatile memories each having therein control-data areas provided for the respective non-volatile memories such that each of the control-data areas stores operation statuses of a corresponding one of said non-volatile memories; and

means for copying contents of a control-data area in a first one of said non-volatile memories to a control-data area in a second one of said non-volatile memories before erasing the control-data area in the first one of said non-volatile memories, thereby effecting continued control of the operation statuses of a corresponding one of said non-volatile memories.

31. A device of storing data in a non-volatile memory medium which permits data writing in a memory area after old data thereof is erased, comprising:

a non-volatile memory having therein a memory area which stores a number of occurrences of a given event; and

means for setting a first bit state in all bits of the memory area as initialization thereof, and for changing one of predetermined bits of the memory area from the first bit state to a second bit state each time the given event occurs, thereby counting the number of occurrences of the given event without a need for erasing the memory area.