Physically Addressed SSD Using MRAM for Flash Table Recovery
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Solution Overview
Problem
Physically addressed Solid State Drives (SSDs) face challenges in reliably preserving flash block management tables during power interruptions, leading to potential data corruption and prolonged system initialization times due to the volatility of flash block management tables stored in system memory without power backup.
Innovation Solution
A computer system with a central processing unit, system memory, and a physically-addressable SSD that includes a flash subsystem and non-volatile memory, where flash tables are maintained and updated in both system memory and MRAM, allowing for the reconstruction of flash tables upon power interruption by using snapshots and updates stored in non-volatile memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If flash block management tables are stored in system memory without power backup, then system initialization speed is improved, but data reliability deteriorates during power interruptions
Solution Approach 1:
The patent applies preliminary action by pre-storing snapshots of flash block management tables in non-volatile memory (flash memory) before power interruptions occur. The system periodically saves table snapshots and maintains update logs in non-volatile storage, so that upon power restoration, the tables can be quickly reconstructed without lengthy re-initialization processes. This resolves the contradiction by preparing data in advance to enable both fast recovery and reliable data preservation.
Solution Approach 2:
The patent uses copying by maintaining multiple copies of flash block management tables across different storage media. Snapshots are copied to non-volatile flash memory, while active tables reside in system memory. Update logs are also copied to non-volatile storage. This multi-copy strategy ensures that if power is interrupted, reliable copies exist in non-volatile memory, enabling fast reconstruction without data loss, thus resolving the contradiction between initialization speed and data reliability.
2Reliability
If flash block management tables are stored in non-volatile memory, then data reliability during power interruptions is improved, but system initialization time increases
Solution Approach 1:
The patent applies segmentation by dividing flash block management tables into multiple components: active tables in system memory for immediate access, periodic snapshots in non-volatile flash memory for reliability, and update logs in non-volatile storage for tracking changes. This segmentation allows the system to initialize quickly by loading only necessary portions from non-volatile storage while maintaining full reliability through distributed storage across multiple media, resolving the contradiction between reliability and initialization speed.
Solution Approach 2:
The patent uses partial action by not requiring complete reconstruction of all table data during initialization. Instead, the system reconstructs only the portions of flash block management tables that are necessary for immediate operation, using snapshots and update logs stored in non-volatile memory. This partial reconstruction approach maintains data reliability while significantly reducing initialization time compared to full reconstruction, resolving the contradiction effectively.
3Reliability
If snapshots and updates are stored in both system memory and MRAM, then data reconstruction capability is improved, but device complexity increases
Solution Approach 1:
The patent uses an intermediary approach by introducing a file system layer and memory management software that mediates between system memory and MRAM storage. This intermediary layer handles the complexity of coordinating snapshots and updates across both memory types, providing a simplified interface to the rest of the system. The file system manages which data resides in which memory type and handles the reconstruction process, thereby improving reconstruction capability while containing complexity within the intermediary layer rather than propagating it throughout the entire system.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution ensures reliable preservation of flash block management tables during power interruptions, reducing data corruption and system initialization delays by using MRAM to store updates and snapshots of flash tables, enabling efficient reconstruction upon power restoration.
Implementation Method 1
non-volatile memory includes updates to the copy of the flash tables and the one or more copies of the flash tables are used to reconstruct the flash tables upon power interruption
Data Source
AI summary
A computer system includes a central processing unit (CPU), a system memory coupled to the CPU and including flash tables, and a physically-addressable solid state disk (SSD) coupled to the CPU. The physically-addressable SSD includes a flash subsystem and a non-volatile memory and is addressable using physical addresses. The flash subsystem includes one or more copies of the flash tables and the non-volatile memory includes updates to the copy of the flash tables. The flash tables include tables used to map logical to physical blocks for identifying the location of stored data in the physically addressable SSD, wherein the updates to the copy of the flash tables and the one or more copies of the flash tables are used to reconstruct the flash tables upon power interruption.