System and method for performing data retention in solid-state memory using copy commands and validity and usage data

摘要

Systems and methods for retaining data in non-volatile solid-state are disclosed in which refresh copy operations are performed on data stored in non-volatile solid-state memory. A controller can comprise a data retention module configured to issue copy commands within different periods of time, and to maintain usage data on a storage subsystem. A refresh copy operation helps ensure that data written to memory retain integrity by causing data to be programmed again onto the memory, which minimizes the risk of data error caused by electron leak in the non-volatile solid-state memory. One or more data structures may be used to determine memory blocks that require refresh copy operations. In one embodiment, a validity bit array is used to track blocks that contain valid data. In another embodiment, a least recently used list is used to track blocks that have been least recently written.