SSD Garbage Collection Stream ID Recovery
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Solution Overview
Problem
Current implementations of multi-streaming and auto-streaming technologies in Solid State Drives (SSDs) lack the ability to effectively associate data with its original stream ID during garbage collection, leading to inefficiencies in grouping data with similar lifetimes for optimal storage and wear management.
Innovation Solution
The proposed solution involves storing stream identifiers and characteristics in SSDs, allowing for the recovery and reuse of stream IDs during garbage collection, enabling data with similar lifetimes to be stored in the same erase block, and optimizing block allocation based on wear levels and stream characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multi-streaming is implemented without storing stream ID with data, then device complexity is reduced, but garbage collection efficiency deteriorates due to inability to associate data with original stream
Solution Approach 1:
The patent segments the storage system into multiple streams, where each stream is identified by a unique stream ID. During garbage collection, the system segments the collection process by identifying valid pages through their stream IDs and grouping them with other valid pages from the same stream, enabling efficient stream-aware garbage collection without requiring extensive additional storage infrastructure.
Solution Approach 2:
The patent applies preliminary action by storing the stream ID with data pages at the time of writing. This preliminary tagging allows the garbage collection process to later identify and associate valid pages with their original streams without requiring complex analysis during the garbage collection phase itself, thus improving efficiency while maintaining relatively simple device architecture.
2Productivity
If stream ID is stored with data, then garbage collection efficiency is improved through better data association, but device complexity increases
Solution Approach 1:
The patent merges the stream ID information with the existing data page structure by storing the stream ID in the same physical location as the data (e.g., in the OOB region of the page). This combining approach allows the system to gain stream identification capability without adding separate storage structures, thus improving garbage collection efficiency while minimizing the increase in device complexity.
Solution Approach 2:
The patent makes the stored stream ID serve multiple functions: it identifies the data's original stream for garbage collection purposes, enables wear leveling across streams, and supports stream-aware allocation decisions. This multi-functionality allows a single simple storage mechanism to deliver multiple benefits, improving productivity without proportionally increasing device complexity.
3Device complexity
If data is not grouped by stream during garbage collection, then device complexity is reduced, but wear management deteriorates due to inability to optimize block allocation
Solution Approach 1:
The patent implements dynamic wear management by using stream IDs to track the wear state of different streams independently. The system dynamically adjusts block allocation decisions based on the wear levels of specific streams, allowing more heavily worn streams to be allocated to fresher blocks while keeping less worn streams on existing blocks, thereby extending overall device lifespan without requiring complex static wear management structures.
Solution Approach 2:
The patent applies feedback mechanisms where the stored stream ID provides information about the data's origin and wear history. This feedback enables the garbage collection and allocation system to make informed decisions about block selection, prioritizing blocks with lower wear for streams that need relocation, thus improving wear management effectiveness while maintaining relatively simple device architecture through intelligent use of stream identification feedback.
Data Source
AI summary
A Solid State Drive (SSD) is disclosed. The SSD may include storage for data and a host interface logic to receive requests from a host machine. The SSD may also include an SSD controller to manage reading data from and writing data to the storage responsive to the requests. The SSD controller may include a flash translation layer to translate logical addresses to physical addresses, a garbage collection logic to perform garbage collection on an erase block that includes a valid page, a stream logic to manage stream characteristics for the data in the valid page, and a restreamer logic to assign the valid page to a new block based on the stream characteristics.