Controller for Segmented SLC and MLC NAND Flash Storage
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Solution Overview
Problem
Existing data storage systems cannot effectively manage single level cell (SLC) and multi level cell (MLC) NAND flash memories as distinct devices, leading to complex data writing and inefficient storage operations.
Innovation Solution
An independent controller is introduced to identify and manage SLC and MLC NAND flash memories as separate storage devices, allowing the host to recognize them as such and direct data storage accordingly, using proprietary or vendor-specific commands and interfaces like PATA or SATA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If both SLC and MLC are disposed in the same host as a single storage device, then hardware cost is reduced and storage capacity is increased, but data management complexity increases and operational efficiency deteriorates
Solution Approach 1:
The patent divides the storage system into two independent storage devices: one dedicated to SLC NAND flash memory and another dedicated to MLC NAND flash memory. Each storage device is managed separately by the host, allowing independent optimization of data placement strategies. This segmentation resolves the management complexity by treating them as distinct entities rather than a unified storage pool, enabling simpler and more efficient data writing operations.
2Productivity
If SLC is used for frequently-accessed data and MLC for general data files, then data access efficiency is improved, but device complexity increases due to sophisticated data management requirements
Solution Approach 1:
The patent implements physical segmentation of storage functions by dedicating SLC storage devices to frequently-accessed data (such as operating system files) and MLC storage devices to general data files. This segmentation enables the host to optimize data access patterns for each storage type independently, achieving high data access efficiency without requiring complex software-based data management systems to handle mixed storage media.
Solution Approach 2:
The patent applies local quality optimization by matching specific storage media characteristics to specific data types: SLC's fast write and read speeds are utilized for frequently-accessed operational data, while MLC's high capacity and cost-effectiveness are utilized for bulk data storage. This localized optimization of storage quality for different data categories achieves high productivity without increasing overall device complexity.
3Quantity of substance
If MLC is used to increase storage capacity, then storage density is improved, but lifespan and reliability deteriorate due to limited write cycles
Solution Approach 1:
The patent segments the storage system to separate reliability-critical functions from capacity-critical functions. SLC storage devices, with their superior write endurance and reliability, are dedicated to storing the operating system and frequently-accessed data that require high reliability. MLC storage devices, with their lower cost and higher capacity, are dedicated to storing less critical general data files. This segmentation allows the system to achieve high total storage capacity while protecting reliability by isolating critical data to the more durable SLC media.
Data Source
AI summary
A system, a controller, and a method for data storage are provided. The system includes a first storage unit, a second storage unit, and a controller. The first storage unit comprises a single-layer structure for storing data, and the second storage unit comprises a multi-layer structure for storing data. The controller is coupled to the first storage unit, the second storage unit, and a host and controls the host to set the first storage unit as a master storage device and set the second storage unit as a slave storage device. As a result, the host can recognize the first storage unit and the second storage unit as two independent storage devices for storing data. Thereby, the data storage process can be simplified.