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

A system for managing the life expectancy of at least one solid state drive (SSD) in a storage subsystem, comprising:

• at least one cache device incorporating the at least one SSD;
• at least one of a back-end disk and a virtual device;
• at least one timer configured to run for a predetermined interval;
• and
• a firmware level operably coupled to the at least one SSD and configured to
• (a) initialize the at least one cache device;
• (b) start the at least one timer;
• (c) determine 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;
• (d) determine a first parameter associated with the remaining life of the at least one SSD at the time of initialization;
• (e) determine a second parameter associated with the power-on time of the at least one SSD at the time of initialization;
• (f) when the at least one timer expires, receive a third parameter associated with the remaining life of the at least one SSD, receive a fourth parameter associated with power-on time of the at least one SSD after initializing the at least one cache device, and restart the at least one timer;
• (g) determine 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;
• (h) determine 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
• (i) when both the second rate of change and the third rate of change are greater than the first rate of change:
• Nock at least one I/O request to the at least one SSD, and redirect the at least one I/O request to at least one of a back-end disk and a virtual device.

A data storage subsystem including a system for managing the life expectancy of at least one solid state drive (SSD) in a storage subsystem, comprising:

• at least one cache device incorporating the at least one SSD;
• at least one of a back-end disk and a virtual device;
• at least one timer configured to run for a predetermined interval;
• and
• a firmware level operably coupled to the at least one SSD and configured to
• (a) initialize the at least one cache device;
• (b) start the at least one timer;
• (c) determine 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;
• (d) determine a first parameter associated with the remaining life of the at least one SSD at the time of initialization;
• (e) determine a second parameter associated with the power-on time of the at least one SSD at the time of initialization;
• (f) when the at least one timer expires, determine a third parameter associated with the remaining life of the at least one SSD, determine a fourth parameter associated with power-on time of the at least one SSD after initializing the at least one cache device, and restart the at least one timer;
• (g) determine 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;
• (h) determine 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
• (i) when both the second rate of change and the third rate of change are greater than the first rate of change:
• block at least one I/O request intended for the at least one SSD, and redirect the at least one I/O request to at least one of a back-end disk and a virtual device;
• and
• (j) when either the second rate of change or the third rate of change is not greater than the first rate of change, resume receipt of the at least one I/O request via the at least one SSD.