Defect management policies for NAND flash memory

摘要

Systems and methods of managing defects in nonvolatile storage systems that can be used to avoid an inadvertent loss of data, while maintaining as much useful memory in the nonvolatile storage systems as possible. The disclosed systems and methods can monitor a plurality of trigger events for detecting possible defects in one or more nonvolatile memory (NVM) devices included in the nonvolatile storage systems, and apply one or more defect management policies to the respective NVM devices based on the types of trigger events that resulted in detection of the possible defects. Such defect management policies can be used proactively to retire memory in the nonvolatile storage systems with increased granularity, focusing the retirement of memory on regions of nonvolatile memory that are likely to contain a defect.

主权项

1. A method of managing defects in a nonvolatile storage system, the nonvolatile storage system including one or more nonvolatile memory (NVM) devices, the method comprising:
monitoring, by an NVM defect management policy engine, a plurality of trigger events for detecting one or more possible defects in an NVM device among the one or more NVM devices, the respective trigger events having corresponding types, the NVM device including a plurality of physical memory pages, each physical memory page including a plurality of NVM storage locations; having monitored a first trigger event among the plurality of trigger events for detecting a possible defect among the one or more possible defects in the NVM device, determining, by the NVM defect management policy engine, a trigger event type among the corresponding types of the respective trigger events that corresponds to the first trigger event, the first trigger event corresponding to a first NVM storage location among the plurality of NVM storage locations included in a respective one of the plurality of physical memory pages of the NVM device; determining, by the NVM defect management policy engine, a likelihood of monitoring a second trigger event among the plurality of trigger events that (1) has a same trigger event type as the first trigger event, and (2) corresponds to a second NVM storage location among the plurality of NVM storage locations included in the respective one of the plurality of physical memory pages of the NVM device; and having determined the likelihood of monitoring the second trigger event, proactively retiring, by the NVM defect management policy engine, the respective one of the plurality of physical memory pages of the NVM device based on the trigger event type of the first trigger event.