Optimistic Read Operation in Non-Volatile Memory
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Solution Overview
Problem
Non-volatile memory systems face inefficiencies in read operations due to the time-consuming process of accessing and performing error correction on directory mappings within the memory array, which hinders improved read efficiency.
Innovation Solution
The implementation of a non-volatile memory system that includes a controller with a sequencer module and a sensing control module, which allows for direct sensing and transfer of data without initial error correction on the directory mappings, and a verification module to ensure data accuracy before transfer to the host.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the controller accesses the directory system in the non-volatile memory array to obtain logical-to-physical address mapping, then the read operation can be completed, but the read time is increased due to the need to retrieve and perform error correction on the mapping
Solution Approach 1:
The patent pre-loads directory mapping entries into a cache memory before they are needed for read operations. When a read request arrives, the mapping is already available in the cache, eliminating the need to retrieve it from the non-volatile memory array at the moment of reading. This preliminary action significantly reduces read access time while maintaining mapping accuracy through pre-performed error correction on the cached mappings.
2Reliability
If error correction is performed on the directory mapping before data retrieval, then data accuracy is ensured, but the overall read efficiency is reduced
Solution Approach 1:
Error correction for directory mappings is performed in advance during background operations or during write operations, and the corrected mappings are stored in cache memory. When read operations occur, the pre-corrected mappings are already available, eliminating the need to perform error correction during the critical read path. This separates the error correction function from the time-sensitive read operation, maintaining both data accuracy and read speed.
Solution Approach 2:
The patent creates copies of directory mapping entries and stores them in a cache memory structure. These copies are pre-processed with error correction and can be quickly retrieved without affecting the original data in the non-volatile memory array. The copy mechanism allows fast access to corrected mappings without compromising the integrity of the source data or slowing down read operations.
Data Source
AI summary
A non-volatile memory system may include a non-volatile memory die storing a requested data set that a host requests to be read. In response to the host request, a copy of a data set may be retrieved from the non-volatile memory die without performing error correction on an entry identifying a physical address where the data set is stored. If the data set copy matches the requested data set, the data set copy may be sent to the host. If the data set copy does not match the requested data set, then error correction may be performed on a copy of the entry to identify the correct physical address where the requested data set is stored. A copy of the requested data set may then be retrieved and sent to the host.