ZNS Parity Swapping to DRAM for SSD RAM Optimization
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Solution Overview
Problem
Storage devices, such as SSDs, face challenges in efficiently managing parity data due to limited RAM capacity, which increases costs and reduces capabilities by consuming valuable RAM space and requiring more RAM to be included.
Innovation Solution
The implementation of a storage device with a controller that utilizes two random access memory units (RAM1 and RAM2) to generate and update parity data across zones, optimizing the use of RAM by copying and updating parity data between these units during write commands, thereby reducing the need for excessive RAM allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If parity data is stored in RAM for each write command, then data protection is improved, but RAM space consumption increases
Solution Approach 1:
The invention divides the storage system into zones, with each zone having its own dedicated parity die. This segmentation allows parity data to be distributed across multiple zones rather than concentrated in a single RAM location, reducing the peak RAM space required at any given time while maintaining data protection for each zone independently.
Solution Approach 2:
The invention moves parity storage from a single-dimension RAM-based approach to a multi-dimensional approach by utilizing multiple dies within the storage array. Parity data is stored in dedicated parity dies associated with each zone, effectively adding a spatial dimension to parity storage and reducing dependency on limited RAM capacity.
2Adaptability or versatility
If more RAM is included to handle parity data, then storage capabilities are improved, but device cost increases
Solution Approach 1:
The invention makes each die in the storage array multi-functional by designating specific dies as parity dies for their respective zones. These parity dies serve dual purposes: they are part of the storage array structure and simultaneously provide data protection functionality, eliminating the need for separate RAM dedicated to parity storage and reducing overall device cost.
Solution Approach 2:
The storage array serves its own parity storage needs through the integrated parity dies within the array structure. Instead of requiring external or separate RAM resources for parity data, the system uses its own storage components (the parity dies) to store parity information, making the system self-sufficient and reducing additional cost.
3Speed
If parity data is stored in a single RAM location, then access speed is improved, but RAM capacity requirements increase
Solution Approach 1:
The invention segments parity data storage across multiple zone-associated parity dies rather than consolidating all parity data in a single RAM location. Each zone's parity data is stored in its associated parity die, allowing for faster localized access to specific zone parity data while distributing the total storage burden across multiple components, effectively reducing the RAM capacity needed for parity operations.
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 zones. A first command to write data to a first zone is received, first XOR data is generated in the RAM1, and the data of the first command is written to the first zone. When a second command to write data to a second zone is received, the generated first XOR data is copied from the RAM1 to the RAM2, and second XOR data for the second zone is copied from the RAM2 to the RAM1. The second XOR data is updated with the second command, and the data of the second command is written to the second zone. The updated second XOR data is copied from the RAM1 to the RAM2.