XOR Parity Management on Physically Addressable SSDs
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Solution Overview
Problem
Conventional physically addressable solid state devices lack a method to control on-device XOR parity, which is essential for mitigating uncorrectable events such as high bit error rates, erase block failure, and die failure, and require host-controlled media operations, precluding automated or device-assisted parity models.
Innovation Solution
A protocol and system that allow host identification and control of parity capabilities, enabling the SSD to perform XOR parity management, including parity accumulation, storage, and rebuild, through administration and I/O commands, thereby offloading these tasks from the host device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If host-controlled media operations are used, then control over parity management is maintained, but device complexity and host processing burden increase
Solution Approach 1:
The SSD device performs XOR parity accumulation, storage, and rebuild operations autonomously without requiring host intervention. The device includes dedicated logic circuits that automatically calculate parity for data blocks, store parity information in designated regions, and perform rebuild operations when media failures occur, enabling the storage device to manage its own error protection
Solution Approach 2:
The parity management functionality is extracted from the host system and embedded directly into the SSD device. This includes extracting the XOR calculation logic, parity storage management, and rebuild operations from the host's responsibility domain and implementing them as self-contained functions within the storage device's controller and media
2Reliability
If XOR parity management is implemented on SSD, then uncorrectable bit errors are reduced, but device complexity increases
Solution Approach 1:
The patent replaces complex software-based parity management mechanisms with dedicated hardware logic circuits implemented directly in the SSD controller. This includes implementing XOR accumulation logic, parity calculation units, and rebuild coordination circuits in hardware, which significantly reduces the computational burden on the host and simplifies the overall system architecture
Solution Approach 2:
The parity management system is segmented into distinct functional modules within the SSD: data block management units, XOR parity calculation logic, parity context buffer management, and rebuild operation coordinators. Each module handles specific aspects of parity management independently, making the complex function more manageable and maintainable
3Reliability
If multiple parity contexts are supported, then error mitigation is enhanced, but device complexity and resource requirements increase
Solution Approach 1:
Multiple parity contexts are implemented using a nested buffer structure where parity context buffers are organized hierarchically. The system maintains multiple nested levels of parity information, with each context having its own dedicated buffer region. This nested organization allows efficient management of multiple parity contexts while optimizing memory resource utilization through shared infrastructure
Data Source
AI summary
An embodiment of a semiconductor apparatus may include technology to provide information related to one or more parity capabilities of a controller and a persistent storage media in response to an inquiry from a host device, and adjust one or more parameters related to the one or more parity capabilities of the controller and the persistent storage media in response to a request from the host device. Other embodiments are disclosed and claimed.