Memory Subsystem Garbage Collection Using Sequence Identifiers
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Solution Overview
Problem
Conventional memory sub-systems face increased write amplification and reduced operating lifespan due to the inefficiency of garbage collection operations, which fail to effectively manage blocks with large amounts of valid cold data, leading to locked capacity and increased rewrite operations.
Innovation Solution
Implementing a garbage collection operation based on a sequence identifier for blocks, where blocks with significant version gaps indicating cold data are identified and their valid data consolidated into fewer blocks, thereby reducing write amplification and increasing available storage capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional garbage collection operations are performed without considering sequence identifiers, then all blocks are treated equally, but this leads to increased write amplification and reduced operating lifespan due to inefficient management of blocks with cold data
Solution Approach 1:
The patent applies local quality by treating different blocks differently based on their sequence identifiers. Blocks with older sequence identifiers (cold data) are identified and excluded from garbage collection, while blocks with newer sequence identifiers are processed normally. This differentiated approach optimizes garbage collection efficiency by avoiding unnecessary read-modify-write operations on cold data blocks, thereby reducing write amplification.
Solution Approach 2:
The patent changes the parameter used for garbage collection selection from random or LRU-based selection to sequence identifier-based selection. By using sequence identifiers as the selection criterion, the system can identify and preserve blocks containing cold data, thereby reducing the amount of data that needs to be rewritten during garbage collection and reducing overall write amplification.
2Quantity of substance
If blocks with cold data are not preserved, then available blocks for garbage collection increase, but operating lifespan decreases due to repeated rewrite operations on the same data
Solution Approach 1:
The patent applies preliminary action by assigning sequence identifiers to blocks before they become candidates for garbage collection. This pre-tagging allows the system to identify cold data blocks in advance and exclude them from garbage collection operations, preventing unnecessary rewrite operations that would reduce the operating lifespan of the memory blocks.
Solution Approach 2:
By applying local quality through sequence identifier-based differentiation, the patent preserves blocks with cold data (indicated by older sequence identifiers) from garbage collection. This selective preservation reduces the number of rewrite operations on these blocks, thereby extending their operating lifespan while still maintaining sufficient available blocks for active data storage.
3Quantity of substance
If all blocks are subjected to garbage collection, then storage capacity is optimized, but performance deteriorates due to increased write operations and time consumption
Solution Approach 1:
The patent changes the selection parameter for garbage collection from uniform treatment of all blocks to sequence identifier-based selection. This parameter change enables the system to quickly identify and skip blocks with cold data (older sequence identifiers), thereby reducing the time required for garbage collection operations while still effectively utilizing storage capacity for active data.
Solution Approach 2:
By applying local quality through differentiated treatment of blocks based on sequence identifiers, the patent reduces garbage collection time by excluding cold data blocks from the collection process. This selective approach maintains storage capacity optimization for active data while significantly reducing the time and computational resources required for garbage collection operations.
Data Source
AI summary
A first block that is assigned a first sequence identifier can be identified. A determination can be made as to whether the assigned first sequence identifier satisfies a threshold sequence identifier condition that corresponds to a difference between the first sequence identifier assigned to the first block and second sequence identifier assigned to a second block. In response to determining that the assigned first sequence identifier satisfies the threshold sequence identifier condition, a media management operation can be performed on the first block.