Patent ID: 8799568

Claim:
A mass storage device, comprising: nonvolatile semiconductor memory configured to cache data, the nonvolatile semiconductor memory having a predetermined usable lifetime; a degradation testing module configured to perform a degradation test on the nonvolatile semiconductor memory to determine an extent to which the nonvolatile semiconductor memory has degraded, wherein the degradation test comprises iteratively performing an operation on the nonvolatile semiconductor memory until the nonvolatile semiconductor memory reaches a predetermined state, wherein the operation comprises an erase operation or a program operation, and determining the extent to which the nonvolatile semiconductor memory has degraded in response to a number of iterations of the operation required for the nonvolatile semiconductor memory to reach the predetermined state; a life monitor module configured to determine whether the nonvolatile semiconductor memory has reached the predetermined usable lifetime in response to the degradation test; and a hard disk controller module configured to suspend the caching of data in the nonvolatile semiconductor memory in response to the nonvolatile semiconductor memory having reached the predetermined usable lifetime, wherein iteratively performing the operation on the nonvolatile semiconductor memory until the nonvolatile semiconductor memory reaches the predetermined state comprises performing the iterations of the operation on a selected area of the nonvolatile semiconductor memory; performing a read of the selected area of the nonvolatile semiconductor memory after each of the iterations is performed; and ending the degradation test in response to the read indicating that the selected area of the nonvolatile semiconductor memory has reached the predetermined state, wherein the predetermined state corresponds to one of (i) a predetermined programmed state or (ii) a predetermined erased state.