Partial CRC Update for Flash Management Unit Integrity
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Solution Overview
Problem
In enterprise storage systems, existing CRC signature methods are inefficient for ensuring data integrity, particularly when updating partial flash management units (FMUs), as they require recalculating the full CRC signature, leading to data protection gaps and increased resource usage.
Innovation Solution
Each sector of a FMU has a distinct CRC signature, which are XORed to create a combined CRC signature. When updating a sector, the old CRC signature is removed and replaced with a new one, and then XORed with the remaining signatures to maintain data integrity without recalculating the entire FMU CRC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a full CRC signature is recalculated for the entire FMU during partial updates, then data integrity is maintained, but write operation complexity and time increase
Solution Approach 1:
The patent divides the FMU into multiple sectors, each with its own independent CRC signature. This segmentation allows partial updates to only recalculate CRC for the specific sector being updated rather than the entire FMU, reducing write operation complexity while maintaining data integrity through selective CRC verification.
Solution Approach 2:
The patent applies partial action by recalculating CRC signatures only for the specific sector being updated rather than performing a full FMU CRC recalculation. This partial approach maintains data integrity for the updated portion without the overhead of processing the entire FMU, thereby reducing write operation complexity.
2Reliability
If a larger CRC signature is used, then error detection capability improves, but memory device resources increase
Solution Approach 1:
The patent segments the total CRC protection into multiple smaller sector-level CRC signatures. Each sector CRC is smaller than a full FMU CRC, reducing the total memory resources required while maintaining equivalent or improved error detection capability through distributed verification across multiple sectors.
Solution Approach 2:
The patent changes the parameter of CRC signature size from a single large FMU-level signature to multiple smaller sector-level signatures. This parameter change reduces the total bit storage required while maintaining error detection capability through the distributed nature of the sector-level CRCs.
3Productivity
If sector-level CRC signatures are used instead of full FMU CRC, then partial update efficiency improves, but CRC management complexity increases
Solution Approach 1:
The patent segments the FMU into sectors with individual CRC signatures, enabling efficient partial updates by only recalculating and storing the CRC for the specific sector being modified. This segmentation improves partial update efficiency while the CRC management complexity is mitigated by the systematic approach of maintaining one CRC per sector.
Solution Approach 2:
The patent prepares sector-level CRC signatures in advance for each sector within the FMU. This preliminary organization of CRC data by sector enables quick identification and update of only the necessary CRC during partial write operations, improving efficiency without significantly increasing management complexity.
Data Source
AI summary
Effective use of cyclic redundancy check (CRC) signatures is achieved where each sector of a flash management unit (FMU) has a distinct CRC signature. The CRC signatures are XORed together to create a total CRC signature for the FMU. When a host device updates a single sector of the FMU, the CRC signature for the updated single sector can be changed by removing the old CRC signature corresponding to the single sector and replacing the old CRC signature with a new CRC signature corresponding to the updated single sector. The old CRC signature is XORed from the total CRC signature and then the new CRC signature is XORed with the remaining CRC signatures to create a new total CRC signature. In so doing, data integrity is ensured.