File System Mapping Table Backup for Rapid NVMe Access
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Solution Overview
Problem
Conventional memory sub-systems face challenges in ensuring reliable and rapid access to file system data due to the latency associated with reconstructing the logical-to-physical mapping table, which can lead to inaccessible critical system data and failure to meet host system timing requirements.
Innovation Solution
A memory sub-system that saves a backup copy of the file system mapping table in a dedicated non-volatile memory area, allowing for access even if the primary mapping table reconstruction fails, and uses a circular buffer to manage SMU remaps efficiently, reducing media endurance issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the logical-to-physical mapping table is reconstructed from scratch, then data integrity is ensured, but access time increases and timing requirements are not met
Solution Approach 1:
The patent pre-allocates a specific management unit (MU) to store file system mapping data before it is needed. This preliminary action allows the mapping data to be readily available when required, eliminating the need for time-consuming reconstruction from scratch while ensuring data integrity through dedicated storage.
Solution Approach 2:
The patent extracts the file system mapping data from the general logical-to-physical mapping table and stores it separately in a dedicated management unit. This separation allows the file system mapping to be accessed independently without requiring reconstruction of the entire mapping table, thus reducing access time while maintaining integrity.
2Reliability
If separate mechanisms are used for host data and file system data, then data accessibility is improved, but device complexity increases
Solution Approach 1:
The patent uses a universal management unit structure that serves dual purposes: storing host data mappings and file system mapping data. This multi-functional approach allows separate handling of different data types while maintaining a unified storage architecture, thereby improving accessibility without proportionally increasing complexity.
Solution Approach 2:
The patent segments the mapping table into different portions, with specific management units allocated for file system data while other MUs handle host data. This segmentation enables independent access and management of different data types using the same underlying storage mechanism, balancing accessibility improvements with controlled complexity.
Data Source
AI summary
A system for file system data access can include memory devices including a non-volatile memory device, as well as a processing device, operatively coupled with the memory devices to perform operations including receiving a file system (FS) write command and determining whether a write count of a physical super management unit (PSMU) of the non-volatile memory device satisfies a threshold criterion. The operations can include, recording a change of a super management unit (SMU) mapping for FS data of an FS mapping table, where the FS mapping table is a portion of a logical-to-physical (L2P) mapping table and performing a move of SMU data corresponding to the change of the SMU mapping. They can also include creating a backup copy of the FS mapping table on the non-volatile memory device, and restoring the FS mapping table from the backup copy of the FS mapping table.