Storage Controller Data Placement via Reclaim Unit Selection
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Solution Overview
Problem
Current storage devices face challenges in efficiently managing data placement due to issues like write amplification and delays caused by ongoing operations on nonvolatile memory, where data is updated by erasing and rewriting, leading to inefficiencies in storage media utilization.
Innovation Solution
A flexible data placement scheme that allows a host to arrange data into reclaim units within a storage device, enabling selection of available reclaim units based on operations and conditions such as read or write operations, wear state, and bandwidth requirements, reducing delays and write amplification by dynamically allocating data across different reclaim units and groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is updated by erasing and rewriting in nonvolatile memory, then data can be stored and updated, but write amplification occurs and storage media utilization becomes inefficient
Solution Approach 1:
The storage medium is divided into multiple reclaim groups, each containing multiple reclaim units. This segmentation allows the system to manage and allocate storage space in smaller, more flexible units, improving storage media utilization by dynamically selecting appropriate reclaim units for new data while avoiding unnecessary erasure of entire blocks.
Solution Approach 2:
The system dynamically selects reclaim units based on real-time conditions such as ongoing operations, wear state, and bandwidth requirements. This dynamic allocation optimizes storage efficiency by placing data in the most suitable reclaim units, reducing write amplification, and improving overall storage media utilization without compromising data reliability.
2Adaptability or versatility
If data is placed in reclaim units based on host arrangement, then data placement flexibility improves, but system complexity increases
Solution Approach 1:
The controller acts as an intermediary between the host and the reclaim units. It manages the complexity of reclaim unit selection, wear state monitoring, and operation coordination, while presenting a simplified interface to the host. This mediator role enables flexible data placement without requiring the host to directly manage the complex details of reclaim unit allocation.
Solution Approach 2:
The system changes multiple parameters simultaneously when selecting reclaim units, including wear state, ongoing operations, and bandwidth requirements. By dynamically adjusting these parameters, the system achieves flexible data placement while managing complexity through a unified selection process that considers all relevant factors.
3Productivity
If reclaim units are selected based on multiple conditions (operations, wear state, bandwidth), then storage performance optimizes, but selection complexity increases
Solution Approach 1:
The system performs preliminary assessments of reclaim unit conditions, including wear state and ongoing operations, before selecting a target reclaim unit for data placement. This preliminary action allows the system to pre-identify suitable reclaim units, reducing the complexity of real-time decision-making and improving storage performance by avoiding suboptimal placements.
Solution Approach 2:
The reclaim unit selection process is dynamic, adapting to changing conditions such as ongoing read/write operations, wear state variations, and bandwidth requirements. This dynamic approach optimizes storage performance by continuously selecting the most appropriate reclaim units, while the systematic evaluation method manages the complexity of considering multiple factors.
Data Source
AI summary
An apparatus may include a storage device that may include at least one storage medium and a controller configured to control the at least one storage medium, wherein the controller may be configured to: receive a write command, wherein the write command may indicate a reclaim unit handle; perform, based on the reclaim unit handle, and based on an operation or condition of the storage device, a selection of a reclaim unit of the at least one storage medium; and store, based on the write command, data to the reclaim unit. The storage medium may include a first reclaim group including the first reclaim unit and a second reclaim group including a second reclaim unit of the at least one storage medium, and the selection of the first reclaim unit may include performing a selection of the first reclaim group.