Active Recycling for Solid State Drive Garbage Collection
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Solution Overview
Problem
Conventional solid state drives (SSDs) face inefficiencies in data management due to the resource- and time-consuming process of garbage collection, which requires reading and rewriting all valid pages from a source block to a new block for erasure, especially when handling frequent data rewrites and maintaining accurate mapping of valid and stale data.
Innovation Solution
Implementing an active recycling method within the SSD, where pages identified for recycling are rewritten to a different block during a read request, utilizing a valid page count table and active recycle table to determine blocks with low valid pages for recycling, thereby reducing processing time and resource consumption during garbage collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional garbage collection is performed by reading and rewriting all valid pages from a source block to a new block, then data erasure is achieved, but processing time and resource consumption increase significantly
Solution Approach 1:
The patent identifies candidate blocks for garbage collection in advance using a block selection module that monitors valid page counts. By pre-identifying blocks with low valid page counts before the actual garbage collection operation, the system prepares the garbage collection queue ahead of time, reducing the processing time when garbage collection is actually triggered.
Solution Approach 2:
The patent extracts only the necessary information (valid page count) from each block to determine garbage collection candidates, rather than processing all pages. The block selection module extracts blocks meeting the garbage collection threshold into a separate queue, separating the identification phase from the execution phase to reduce overall processing time.
2Productivity
If all valid pages are rewritten to a new block for garbage collection, then source block erasure is enabled, but resource consumption and processing overhead increase
Solution Approach 1:
The patent performs partial garbage collection by only copying pages that are marked for recycling, rather than copying all valid pages in a block. The active recycling mechanism identifies specific pages that can be recycled and copies only those pages to new blocks, reducing the total number of write operations and associated energy consumption while still achieving the goal of freeing up source blocks.
3Loss of time
If active recycling is implemented by rewriting pages during read requests, then garbage collection processing time is reduced, but additional write operations increase overall workload
Solution Approach 1:
The patent merges the garbage collection function with the normal read operation. When a read request is received, the system checks if the requested page belongs to a candidate block for garbage collection. If so, the page is copied to a new block as part of the read operation itself, combining two functions (reading and garbage collection) into a single operation flow, thereby reducing overall processing time without significantly increasing complexity.
Solution Approach 2:
The system performs self-service garbage collection by automatically identifying and recycling pages during normal operations. The active recycling mechanism monitors block states and automatically triggers page copying when conditions are met, without requiring external intervention or complex scheduling, allowing the SSD to manage its own garbage collection needs efficiently.
Data Source
AI summary
A solid state drive and a method for providing active recycling for the solid state drive are disclosed. The solid state drive includes a plurality of blocks and each of the plurality of blocks includes a plurality of pages. The method steps include receiving a read request from a data requester; identifying at least one page containing data requested by the read request; determining whether the at least one page belongs to a block identified for active recycling; writing the at least one page to a different block when the at least one page belongs to the block identified for active recycling; and sending the at least one page to the data requester in response to the read request.