Storage Controller Parity Buffering for SSD Write Optimization
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Solution Overview
Problem
Storage devices, such as SSDs, face inefficiencies due to limited RAM capacity for parity data generation and slower data transfer to NAND, leading to increased costs and reduced capabilities, as parity data generation occurs simultaneously with data writing, consuming valuable RAM space and slowing down data transfer.
Innovation Solution
Implementing a controller with a temporary buffer in RAM1 to update and store parity data in RAM2, optimizing data transfer speeds by restricting the host to a minimum write size, allowing for simultaneous writing and parity data updates, and copying previous parity data to the temporary buffer when commands are received.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If parity data is generated for each write command simultaneously with data writing, then data protection is improved, but RAM space consumption increases and data transfer speed decreases
Solution Approach 1:
The patent applies preliminary action by pre-fetching parity data from NAND memory into RAM before the actual write operation occurs. This allows the parity data to be ready in fast memory when needed, avoiding the need to generate it simultaneously during the write operation, thus reducing RAM consumption during critical operations while maintaining data protection.
Solution Approach 2:
The patent segments the write operation into distinct phases: data writing phase and parity generation phase. By separating these operations, the system can write data to NAND without simultaneously generating parity in RAM, reducing peak RAM usage while still providing data protection through the segmented parity generation process.
2Productivity
If data transfer speed to NAND is increased, then productivity is improved, but a bottleneck occurs when simultaneously generating or updating parity data
Solution Approach 1:
The patent uses preliminary action by pre-loading parity data into RAM before the write operation. This preparation eliminates the bottleneck that would occur if parity data had to be generated or fetched from NAND during the high-speed data transfer, allowing continuous fast writing without interruption.
Solution Approach 2:
The patent introduces RAM as an intermediary buffer between NAND memory and the parity generation process. By staging parity data in RAM, the system decouples the slow NAND access from the fast data transfer path, eliminating the bottleneck while maintaining data integrity through the intermediary buffering mechanism.
3Reliability
If more RAM is included in the storage device, then parity data generation capability is improved, but device cost increases
Solution Approach 1:
The patent applies preliminary action by pre-fetching and staging parity data in RAM before write operations. This approach allows the system to maintain strong parity generation capability using a smaller amount of RAM, as the pre-staged data reduces the need for large RAM buffers during critical write operations, thereby lowering device cost while preserving reliability.
4Productivity
If minimum write size is restricted, then data transfer speed optimization is improved, but host flexibility decreases
Solution Approach 1:
The patent applies parameter changes by implementing a minimum write size threshold that triggers optimized transfer paths. This parameter-based approach allows the system to maintain high data transfer speeds for qualifying operations while still accepting smaller writes through alternative paths, balancing performance optimization with host flexibility through conditional parameter adjustment.
Data Source
AI summary
The present disclosure generally relates to methods of operating storage devices. The storage device comprises a controller comprising first random access memory (RAM1), second random access memory (RAM2), and a storage unit divided into a plurality of streams. By restricting the host to have a minimum write size, the data transfer speed to RAM2, RAM1, and the storage unit can be optimized. A temporary buffer is utilized within the RAM1 to update parity data for the corresponding commands. The parity data is updated in the RAM1 and written to the RAM2 in the corresponding stream. The parity data may be copied from the RAM2 to the RAM1 to update the parity data in the temporary buffer when commands are received to write data to corresponding streams. As the parity data is updated, the corresponding command is simultaneously written to the corresponding stream.