System and method of life management for low endurance SSD NAND devices used as secondary cache

摘要

A system and method for managing the life expectancy of at least one solid state drive (SSD) within a cache device of a storage subsystem includes determining a baseline rate of decline for each SSD based on its guaranteed life expectancy. At intervals, each SSD of the cache device is polled for remaining life and power-on time, and a current rate of decline (based on time since initialization) and a cumulative rate of decline (based on total lifespan of the SSD) is determined. When both the current rate of decline and the cumulative rate of decline exceed the baseline rate of decline for any SSD of the cache device, write requests to that SSD are blocked and redirected to the virtual device until either the current rate of decline or cumulative rate of decline drop below the baseline rate.

主权项

1. A method for managing the life expectancy of at least one solid state drive (SSD) in a storage subsystem, comprising:
initializing at least one cache device including the at least one SSD; determining a first rate of change representing a relationship between the rated life expectancy of the at least one SSD and the chronological lifespan of the at least one SSD; determining a first parameter associated with the remaining life of the at least one SSD; determining a second parameter associated with the power-on time of the at least one SSD; starting at least one timer to run for a predetermined interval, when the at least one timer expires, determining a third parameter associated with the remaining life of the at least one SSD, determining a fourth parameter associated with power-on time of the at least one SSD after initializing the at least one cache device, and restarting the at least one timer; determining a second rate of change representing a relationship between life expended by the at least one SSD after initializing the at least one cache device and power-on time of the at least one SSD after initializing the at least one cache device; determining a third rate of change representing a relationship between total life expended by the at least one SSD and total power-on time of the at least SSD; and when both the second rate of change and the third rate of change are greater than the first rate of change:
blocking at least one I/O request to the at least one SSD, andredirecting the at least one I/O request to at least one of a back-end disk and a virtual device.