Storage device cache

摘要

A method of operating a mass storage device including caching data in a nonvolatile semiconductor memory, in which the nonvolatile semiconductor memory has a predetermined usable lifetime. The method includes iteratively performing an operation on the nonvolatile semiconductor memory until the nonvolatile semiconductor memory reaches a predetermined state, wherein the operation includes an erase operation or a program operation; and determining an 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. The method also includes determining whether the nonvolatile semiconductor memory has reached the predetermined usable lifetime in response to the extent to which the nonvolatile semiconductor memory has degraded. The method further includes, in response to the nonvolatile semiconductor memory having reached the predetermined usable lifetime, suspending the caching of data in the nonvolatile semiconductor memory.

主权项

1. 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, anddetermining 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; andending 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.