Wear leveling in non-volatile memories
Systems and methods for wear leveling in non-volatile memories (NVMs) are illustrated. One such system includes a first non-volatile memory configured to store information from a host, a second non-volatile memory storing a plurality of cumulative control states, each indicative of a state of random mappings between physical block addresses (PBAs) and logical block addresses (LBAs) of the first non-volatile memory, and a plurality of control states, an access network configured to translate LBAs to PBAs based on the plurality of cumulative control states, a background swap scheduler configured to swap PBAs assigned to LBAs based on the plurality of control states, and a controller configured to sequentially advance through the plurality of cumulative control states and the plurality of control states.
1. A non-volatile memory system configured for wear leveling, the system comprising:
a first non-volatile memory configured to store information from a host;
a second non-volatile memory storing a plurality of cumulative control states, each indicative of a state of random mappings between physical block addresses (PBAs) and logical block addresses (LBAs) of the first non-volatile memory, and a plurality of control states;
an access network configured to translate LBAs to PBAs based on the plurality of cumulative control states;
a background swap scheduler configured to swap PBAs assigned to LBAs based on the plurality of control states; and
a controller configured to sequentially advance through the plurality of cumulative control states and the plurality of control states.
2. The system of claim 1 , wherein the second non-volatile memory comprises a read only memory (ROM).
3. The system of claim 1 :
wherein the cumulative control state comprises a first cumulative control state and a second cumulative control state;
wherein the control state comprises a first control state and a second control state; and
wherein the second cumulative control state is a function of the first cumulative control state and the second control state.
4. The system of claim 3 , wherein the second cumulative control state comprises switch settings used to achieve a sort of a permutation of the first cumulative control state where the permutation is generated using the second control state.
5. The system of claim 1 , further comprising:
a mapping state generator configured to change from a first memory map to a second memory map after the background swap scheduler swaps a preselected number of PBAs;
wherein the first memory map and the second memory map each comprises a preselected number of PBAs.
6. The system of claim 1 , wherein the background swap scheduler is configured to swap PBAs after a preselected number of accesses of the first non-volatile memory.
7. The system of claim 6 , wherein preselected number of accesses comprises 100 writes of the first non-volatile memory.
8. The system of claim 1 , wherein the access network is further configured to:
generate a first PBA candidate from a LBA using a first function;
generate a second PBA candidate from the LBA using a second function; and
select either the first PBA candidate or the second PBA candidate for data access based on information related to a background swap of data stored at the first PBA candidate and a background swap of data stored at the second PBA candidate.
9. The system of claim 8 , wherein at least one of the first function or the second function comprises a function performed by at least one of a multi-stage interconnection network or a block cipher.
10. A method for wear leveling in a non-volatile memory system, the method comprising:
storing information in a first non-volatile memory;
storing a plurality of cumulative control states, each indicative of a state of random mappings between physical block addresses (PBAs) and logical block addresses (LBAs) of the first non-volatile memory, and a plurality of control states in a second non-volatile memory;
translating LBAs to PBAs based on the plurality of cumulative control states;
swapping PBAs assigned to LBAs based on the plurality of control states; and
advancing sequentially through the plurality of cumulative control states and the plurality of control states.
11. The method of claim 10 , wherein the storing the plurality of cumulative control states and the plurality of control states comprises:
calculating the plurality of cumulative control states and the plurality of control states; and
storing the plurality of cumulative control states and the plurality of control states.
12. The method of claim 10 , wherein the second non-volatile memory comprises a read only memory (ROM).
13. The method of claim 10 :
wherein the cumulative control state comprises a first cumulative control state and a second cumulative control state;
wherein the control state comprises a first control state and a second control state; and
wherein the second cumulative control state is a function of the first cumulative control state and the second control state.
14. The method of claim 13 , wherein the second cumulative control state comprises switch settings used to achieve a sort of a permutation of the first cumulative control state where the permutation is generated using the second control state.
15. The method of claim 10 , further comprising:
changing from a first memory map to a second memory map after swapping a preselected number of PBAs;
wherein the first memory map and the second memory map each comprises a preselected number of PBAs.
16. The method of claim 10 , wherein the swapping PBAs assigned to LBAs based on the control state comprises swapping PBAs after a preselected number of accesses of the first non-volatile memory.
17. The method of claim 16 , wherein preselected number of accesses comprises 100 writes of the first non-volatile memory.
18. The method of claim 10 , further comprising:
generating a first PBA candidate from a LBA using a first function;
generating a second PBA candidate from the LBA using a second function; and
selecting either the first PBA candidate or the second PBA candidate for data access based on information related to a background swap of data stored at the first PBA candidate and a background swap of data stored at the second PBA candidate.
19. The method of claim 18 , wherein at least one of the first function or the second function comprises a function performed by at least one of a multi-stage interconnection network or a block cipher.
20. A non-volatile memory system configured for wear leveling, the system comprising:
a first non-volatile means for storing information;
a second non-volatile means for storing a plurality of cumulative control states, each indicative of a state of random mappings between physical block addresses (PBAs) and logical block addresses (LBAs) of the first non-volatile means, and a plurality of control states;
means for translating LBAs to PBAs based on the plurality of cumulative control states;
means for swapping PBAs assigned to LBAs based on the plurality of control states; and
means for advancing sequentially through the plurality of cumulative control states and the plurality of control states.
21. The system of claim 20 :
wherein the cumulative control state comprises a first cumulative control state and a second cumulative control state;
wherein the control state comprises a first control state and a second control state; and
wherein the second cumulative control state is a function of the first cumulative control state and the second control state.
22. The system of claim 21 , wherein the second cumulative control state comprises switch settings used to achieve a sort of a permutation of the first cumulative control state where the permutation is generated using the second control state.
23. The system of claim 20 , further comprising:
means for changing from a first memory map to a second memory map after swapping a preselected number of PBAs;
wherein the first memory map and the second memory map each comprises a preselected number of PBAs.
24. The system of claim 20 , wherein the means for swapping PBAs assigned to LBAs based on the control state comprises means for swapping PBAs after a preselected number of accesses of the first non-volatile means.
25. The system of claim 24 , wherein the preselected number of accesses comprises 100 writes of the first non-volatile means.
26. The system of claim 20 , further comprising:
means for generating a first PBA candidate from a LBA using a first function;
means for generating a second PBA candidate from the LBA using a second function; and
means for selecting either the first PBA candidate or the second PBA candidate for data access based on information related to a background swap of data stored at the first PBA candidate and a background swap of data stored at the second PBA candidate.