Apple Inc.
Schemes for protecting data in NVM device using small storage footprint

Abstract:

A memory system includes a Nonvolatile Memory (NVM) and storage circuitry. The NVM includes memory cells organized in multiple memory blocks that each includes multiple Word Lines (WLs). The storage circuitry assigns in a recovery scheme, data pages to predefined parity groups, including assigning to a parity group multiple data pages of two or more different bit-significance values in a common group of the memory cells in a WL. The storage circuitry calculates redundancy data over the data pages of a given parity group in accordance with the recovery scheme and stores the redundancy data in a dedicated group of the memory cells. The storage circuitry reads a data page belonging to the given parity group, and upon detecting a read failure, recovers the data page based on other data pages in the given parity group and on the redundancy data calculated for the given parity group.