Host-Storage Log Coordination for Lower Garbage Collection
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Solution Overview
Problem
Conventional memory sub-systems face inefficiencies in garbage collection, leading to increased write amplification and reduced performance and endurance due to the lack of effective coordination between host systems and memory sub-systems, particularly with flexible direct placement (FDP) technologies.
Innovation Solution
The implementation of host system coordination with memory sub-systems to schedule operations that reduce garbage collection, using reclaim units (RUs) for orderly data management, minimizing intrusive changes to existing protocols, and leveraging flexible direct placement (FDP) to group data for simultaneous erasure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional memory sub-systems perform garbage collection independently without host coordination, then the memory sub-system can maintain autonomous operation, but write amplification increases and performance deteriorates
Solution Approach 1:
The host system performs preliminary actions by scheduling write operations to complete before the memory sub-system initiates garbage collection. The host coordinates its write operations to finish evicting data from reclaim units before the memory sub-system erases those units, thereby avoiding write amplification and improving performance.
2Loss of energy
If the host system coordinates write operations to complete before garbage collection, then write amplification is reduced, but the host must track and manage reclaim unit usage complexity increases
Solution Approach 1:
The memory sub-system provides feedback to the host system by exposing the usage level of reclaim units through log pages or other communication mechanisms. This feedback enables the host to track reclaim unit usage and schedule its write operations accordingly, reducing write amplification while managing coordination complexity through information exchange.
3Productivity
If flexible direct placement is used to group data for simultaneous erasure, then garbage collection efficiency improves, but protocol modifications are required
Solution Approach 1:
The invention makes the data placement directive mechanism universal by enabling it to serve dual purposes: traditional data placement and garbage collection coordination. The same directive infrastructure used for normal write operations is leveraged to control garbage collection behavior, eliminating the need for separate protocol modifications and maintaining backward compatibility.
Data Source
AI summary
A memory sub-system, having: a host interface; memory cells having a storage capacity; and a controller configured to provide data storage services over the host interface using the storage capacity. The controller is configured to provide, in a log file, information related to garbage collection, such as a current usage level of the memory cells, a target usage level of the memory cells which when reached can trigger garbage collection in the memory sub-system, planned targets of garbage collection when the target usage level is reached. A host system can extract information from the log file to schedule and perform operations to reduce garbage collection in the memory sub-system.