Non-volatile semiconductor storage device
According to one embodiment, there is provided a non-volatile semiconductor storage device including a non-volatile memory, a monitoring section, a determining section, and a notification processing section. The non-volatile memory includes a plurality of memory cells driven by word lines and a voltage generating section that generates a read voltage to be applied to the word lines. The monitoring section monitors a change in a threshold distribution of the plurality of memory cells upon performing a read processing to read data from the plurality of memory cells by applying the read voltage to the word lines. The determining section determines a degree of deterioration of the non-volatile memory in accordance with a monitoring result by the monitoring section. The notification processing section notifies a life of the non-volatile memory in accordance with a determining result by the determining section.
1. A storage system which is connectable to a host apparatus including a display device, the storage system comprising:
a non-volatile memory including a plurality of memory cells;
a controller configured to perform a read processing to read data from the plurality of memory cells, to obtain a distribution of read-related parameters which indirectly indicates a change in a threshold distribution, to determine a degree of deterioration of the non-volatile memory based on the obtained distribution of the read-related parameters, and to notify, on the display device through the host apparatus, a life of the non-volatile memory based on the determined degree of deterioration of the non-volatile memory.
2. The storage system according to claim 1 ,
wherein the controller is further configured to compare the obtained distribution with a first threshold to determine the degree of deterioration of the non-volatile memory.
3. The storage system according to claim 2 ,
wherein the controller is further configured to compare a comparison result with a second threshold to determine the degree of deterioration of the non-volatile memory.
4. The storage system according to claim 1 ,
wherein the read-related parameters include a number of reading operations in a read processing until the read processing succeeds while repeatedly performing the read processing by gradually changing a read voltage in one of an increasing direction or a lowering direction.
5. The storage system according to claim 4 ,
wherein the controller is further configured to compare the obtained distribution with a number threshold to determine the degree of deterioration of the non-volatile memory.
6. The storage system according to claim 5 ,
wherein the controller is further configured to compare a comparison result with a frequency threshold to determine the degree of deterioration of the non-volatile memory.
7. The storage system according to claim 1 ,
wherein the read-related parameters include an amount of change of a read voltage from a default value in a read processing when the read processing succeeds while repeatedly performing the read processing by gradually changing a read voltage in one of an increasing direction or a lowering direction.
8. The storage system according to claim 7 ,
wherein the controller is further configured to compare the obtained distribution with a changing amount threshold to determine the degree of deterioration of the non-volatile memory.
9. The storage system according to claim 8 ,
wherein the controller is further configured to compare a comparison result with a frequency threshold to determine the degree of deterioration of the non-volatile memory.
10. The storage system according to claim 1 ,
wherein the read-related parameters include a number of bit errors in data in the plurality of memory cells in performing a read processing.
11. The storage system according to claim 10 ,
wherein the controller is further configured to compare the obtained distribution with a number threshold to determine the degree of deterioration of the non-volatile memory.
12. The storage system according to claim 11 ,
wherein the controller is further configured to compare a comparison result with a frequency threshold to determine the degree of deterioration of the non-volatile memory.
13. The storage system according to claim 1 ,
wherein the read-related parameters include a number of reading operations in a read processing until the read processing succeeds or an amount of change of a read voltage from a default value in a read processing when the read processing succeeds, while repeatedly performing the read processing by gradually changing a read voltage in both of an increasing direction and a lowering direction.
14. The storage system according to claim 13 ,
wherein the controller is further configured to compare the obtained distribution with a number threshold to determine the degree of deterioration of the non-volatile memory.
15. The storage system according to claim 14 ,
wherein the controller is further configured to compare a comparison result with a frequency threshold to determine the degree of deterioration of the non-volatile memory.
16. An information processing system comprising a host apparatus and a storage device, the host apparatus including a display device, wherein
the storage device includes:
a non-volatile memory including a plurality of memory cells; and
a controller configured to perform a read processing to read data from the plurality of memory cells, to obtain a distribution of read-related parameters which indirectly indicates a change in a threshold distribution, to determine a degree of deterioration of the non-volatile memory based on the obtained distribution of the read-related parameters, and to supply the display device with information regarding a life of the non-volatile memory based on the determined degree of deterioration of the non-volatile memory, and
the display device in the host apparatus performs a notification by the supplied information regarding the life of the non-volatile memory.
17. The information processing system according to claim 16 ,
wherein the controller is further configured to compare the obtained distribution with a first threshold to determine the degree of deterioration of the non-volatile memory.
18. The information processing system according to claim 17 ,
wherein the controller is further configured to compare a comparison result with a second threshold to determine the degree of deterioration of the non-volatile memory.
19. The information processing system according to claim 16 ,
wherein the read-related parameters include a number of bit errors in data in the plurality of memory cells in performing a read processing.
20. The information processing system according to claim 16 ,
wherein the read-related parameters include a number of reading operations in a read processing until the read processing succeeds or an amount of change of a read voltage from a default value in a read processing when the read processing succeeds, while repeatedly performing the read processing by gradually changing a read voltage in both of an increasing direction and a lowering direction.