Memory Defect Signature Identification in Non-Volatile Storage
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Solution Overview
Problem
Non-volatile storage devices face challenges in reliably and quickly locating memory defect lists, as these lists are not consistently stored in the same location across devices and can become difficult to access due to modifications over time.
Innovation Solution
Storing a memory defect list with a unique signature in the metadata portion of pages allows for efficient location and maintenance of both original and updated defect lists, ensuring access to manufacturing defects and current defective blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a memory defect list is stored in non-volatile storage device, then defect location information is preserved, but the list becomes difficult to locate reliably and quickly due to modifications over time
Solution Approach 1:
The patent applies preliminary action by pre-storing a signature value in the metadata portion of pages at the time of defect list creation. This signature acts as a pre-placed marker that enables quick location of the defect list without requiring time-consuming searches through modified storage locations, thus resolving the contradiction between preserving defect information and maintaining quick accessibility.
Solution Approach 2:
The patent uses an intermediary approach by introducing a signature value as a mediator between the defect list data and the search process. This signature stored in metadata serves as a reference point that mediates the location process, allowing the system to quickly find the defect list despite changes in storage location or modifications over time.
2Adaptability or versatility
If defect list location is made flexible to accommodate device variations, then adaptability improves, but consistency in locating the list deteriorates
Solution Approach 1:
The patent implements feedback by storing a signature value in the metadata portion of pages that reflects the actual location of the defect list. This signature acts as feedback information that guides the search process, allowing the system to adapt to different storage locations while maintaining consistent and reliable location through the signature-based search mechanism.
3Measurement precision
If original defect list is maintained separately from updated lists, then manufacturing defect tracking is accurate, but device complexity increases
Solution Approach 1:
The patent applies segmentation by separating the defect list into an original manufacturing defect list and an updated defect list, each maintained in distinct portions of storage. This segmentation allows accurate tracking of manufacturing defects while managing complexity through structured organization, where the original list preserves initial defect information and the updated list incorporates subsequent changes.
Data Source
AI summary
A non-volatile storage subsystem is disclosed that implements a process for reliably managing memory defect information. In one embodiment, a list indicating the locations of defective memory locations is stored in a non-volatile storage device along with a signature that can be used to identify the location of the stored defect list. The stored list may relate to memory defects that are associated with, or developed in connection with, a manufacturing process of the storage device. The signature may be stored in a metadata portion of one or more pages in which the list is stored.