Compressed Page Packing Across ECC Codewords With Less Straddling
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Solution Overview
Problem
Conventional data storage systems using Flash-based SSDs face inefficiencies due to fixed payload sizes of ECC codewords, which lead to straddling issues when packing compressed logical pages, resulting in increased read amplification and latency, especially when compressed pages have varying lengths.
Innovation Solution
A method that dynamically packs compressed logical pages into ECC codewords by identifying open codewords with sufficient space and minimizing straddling, using adaptive algorithms to manage logical capacity loss and optimize ECC container usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If compressed logical pages are packed into fixed-size ECC codeword payloads, then storage capacity utilization is improved, but straddling occurs causing increased read amplification and latency
Solution Approach 1:
The patent implements dynamic packing algorithms that adaptively determine whether to pack compressed logical pages into single ECC codewords or allow straddling across multiple codewords based on current system state, compression ratios, and performance metrics. This dynamic approach resolves the contradiction by flexibly adjusting packing behavior to optimize both capacity utilization and read latency under different operating conditions
Solution Approach 2:
The system changes packing parameters such as threshold values for allowable straddling, codeword selection criteria, and capacity loss limits to balance between full payload utilization and minimizing read amplification. By adjusting these parameters dynamically, the system achieves optimal performance across varying workload characteristics
2Productivity
If compressed logical pages are packed to fill entire ECC codeword payloads, then storage efficiency is improved, but logical capacity loss increases
Solution Approach 1:
The patent applies partial packing strategies where compressed logical pages are packed into ECC codeword payloads only to the extent necessary to achieve acceptable storage efficiency without excessive capacity loss. The system allows partial utilization of codeword payloads when full utilization would cause unacceptable capacity loss, thereby optimizing the trade-off between storage efficiency and capacity retention
3Device complexity
If conventional fixed packing methods are used, then implementation simplicity is maintained, but performance degrades due to straddling across physical page boundaries
Solution Approach 1:
The patent segments the packing decision-making process into distinct phases: identification of compressed logical pages, evaluation of packing options, selection of target ECC codewords, and execution of packing operations. This segmented approach maintains implementation simplicity by breaking down the complex packing problem into manageable steps while improving read speed through optimized packing strategies
Data Source
AI summary
A computer-implemented method, according to one embodiment, includes: repeating the following sequence at least until a page stripe of a memory cache has at least a predetermined amount of data stored therein: finding an open codeword having an amount of available space which is greater than or equal to a size of a compressed logical page, and storing the compressed logical page in the open codeword having the amount of available space which is greater than or equal to a size of the compressed logical page. Other systems, methods, and computer program products are described in additional embodiments.