Systems and methods for measuring the useful life of solid-state storage devices
View Patent ↗A non-volatile solid-state storage subsystem, such as a non-volatile memory device, maintains usage statistics reflective of the wear state, and thus the remaining useful life, of the subsystem's memory array. A host system reads the usage statistics information, or data derived therefrom, from the subsystem to evaluate the subsystem's remaining life expectancy. The host system may use this information for various purposes, such as to (a) display or report information regarding the remaining life of the subsystem; (b) adjust the frequency with which data is written to the subsystem; and/or (c) select the type(s) of data written to the subsystem.
1. A data storage system, comprising:
a non-volatile memory array; and
a controller configured to:
maintain usage information and corresponding temporal data in the non-volatile memory array, the usage information reflective of a current wear level of the non-volatile memory array, the usage information comprising a plurality of counter values associated with a plurality of data blocks of the non-volatile memory array, wherein the controller is configured to:
add the plurality of counter values to derive a sum of the counter values; and
divide the sum of the counter values by a pre-determined threshold value, the threshold value being reflective of an estimated total number of program/erase cycles of the non-volatile memory array;
estimate an amount of the remaining useful life of the data storage system based on the usage information obtained from two or more different time periods; and
in response to a request received from a host system, provide the estimated amount of the remaining useful life to the host system.
2. The data storage system of claim 1 , wherein the temporal data comprises one or more timestamps.
3. The data storage system of claim 1 , wherein in response to the request received from the host system, the controller is further configured to provide to the host system the usage information and corresponding data values.
4. The data storage system of claim 1 , wherein estimating the amount of the remaining useful life of the data storage system is based on a result of dividing the sum of the counter values by the pre-determined threshold.
5. The data storage system of claim 1 , wherein at least one counter value is associated with a block of the plurality of data blocks and the at least one counter value is incremented when the associated block is erased.
6. A data storage system in combination with a host system, the data storage system comprising:
a non-volatile memory array comprising a plurality of data blocks; and
a controller configured to maintain usage information and corresponding temporal data in the non-volatile memory array, the usage information reflecting a number of times the plurality of data blocks have been erased;
wherein the host system is configured with:
a first program module configured to:
retrieve the usage information and corresponding temporal data, the usage information being from two or more different time periods; and
estimate an amount of the remaining useful life of the data storage system using the retrieved usage information from two or more different time periods; and
a second program module configured to generate a graphical display indicating the estimated amount of the remaining useful life and a measure of utilization of the data storage system relative to a percentage scale.
7. The data storage system of claim 6 , wherein the temporal data comprises one or more timestamps.
8. The data storage system of claim 6 , wherein the graphical display is configured as a meter.
9. The data storage system of claim 6 , wherein the percentage scale corresponds to a specified endurance of the data storage system.
10. The data storage system of claim 8 , wherein the meter is configured to provide indicia of a threshold relative to the percentage scale.
11. The data storage system of claim 10 , wherein the threshold is less than the specified endurance of the storage system.
12. The data storage system of claim 8 , wherein the meter is configured to provide indicia of a time displayed relative to the percentage scale so as to indicate the utilization of the data storage system relative to the percentage scale during a predetermined time period.
13. The data storage system of claim 6 , wherein the graphical display is configured as a bar chart.
14. The data storage system of claim 6 , wherein the usage information comprises a first set of usage information that is specific to a first period of usage and a second set of usage information that is specific to a second period of usage that is separate from the first period.
15. A non-transitory computer-readable medium having stored thereon a computer program which, when executed by a host computer, causes the host computer to at least:
retrieve usage information from a data storage system that is configured to maintain such usage information, the usage information being reflective of a number of program/erase cycles that have been executed by the data storage system in a non-volatile memory array;
estimate an amount of the remaining useful life of the data storage system based on the usage information; and
adjust a policy for storing data in the data storage system based at least on a criticality of data to be stored and the estimated amount of the remaining useful life, wherein adjusting the policy includes varying a frequency with which data is stored in the data storage system.
16. The computer-readable medium of claim 15 , wherein the frequency with which data is stored is reduced in response to determining that there is a reduction in the estimated amount of the remaining useful life.
17. The computer-readable medium of claim 15 , wherein the computer program further causes the host computer to adjust the policy for storing data so that critical data is stored in the data storage system when the estimated amount of the remaining useful life is above a threshold.
18. The computer-readable medium of claim 15 , wherein the data storage system is configured to maintain user information in a non-user-data memory area of the non-volatile memory array.
19. The computer-readable medium of claim 15 , wherein the computer program further causes the host computer to use the usage information to generate a graphical display depicting a remaining useful life of the data storage system, the display including an indicia of the estimated amount of the remaining useful life.
20. The computer-readable medium of claim 15 , wherein the usage information comprises a plurality of counter values indicating the number of times a plurality of blocks of the non-volatile memory array have been erased, and the computer program is configured to use the counter values to estimate the amount of the remaining useful life.