Nonvolatile Memory Prefetching to Reduce Sequential Read Latency
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Solution Overview
Problem
Existing storage devices face challenges in improving operating speed and efficiency, particularly in managing data access and prefetching operations in nonvolatile memory devices.
Innovation Solution
A storage device with a nonvolatile memory and a controller that performs zone-based data management, including prefetch operations by reading sequential logical addresses and storing data in an internal buffer without additional requests, and utilizing zone maps and internal buffers to optimize data allocation and access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If sequential reads are performed in nonvolatile memory devices, then data access speed is improved, but the complexity of managing zones and prefetch operations increases
Solution Approach 1:
The storage device is divided into multiple zones, each with its own zone buffer, allowing independent management and prefetch operations. This segmentation enables parallel data retrieval across different zones while reducing the complexity of managing large datasets through localized control.
Solution Approach 2:
The controller performs preliminary prefetch operations by reading data from nonvolatile memory before it is actually requested by the host device. This preliminary action stores data in zone buffers in advance, eliminating wait times during subsequent sequential reads and improving overall data access speed.
2Productivity
If prefetch operations are implemented to improve operating speed, then data retrieval efficiency increases, but the risk of data loss or corruption increases
Solution Approach 1:
Zone buffers serve as intermediary storage between the nonvolatile memory and the host device. These buffers temporarily hold prefetched data, allowing the system to retrieve data efficiently while maintaining a clear separation between storage layers, which helps prevent data corruption during prefetch operations.
Solution Approach 2:
The controller manages zone buffers with tracking mechanisms that monitor data status and availability. This feedback system ensures that prefetch operations are coordinated properly with actual data requests, preventing data loss by aligning prefetch timing with real needs while maintaining data integrity.
3Speed
If multiple zone buffers are used to manage sequential reads, then operating speed is improved, but the device complexity and resource consumption increase
Solution Approach 1:
The system divides the storage space into multiple zones, each with its own dedicated zone buffer. This segmentation allows parallel prefetch operations across different zones, improving overall operating speed while keeping each buffer's management simple and independent.
Solution Approach 2:
Each zone buffer serves multiple functions: it stores prefetched data, acts as a temporary buffer during sequential reads, and enables parallel data retrieval operations. This multi-functionality reduces the need for additional specialized components, managing complexity while improving performance.
Data Source
AI summary
A storage device, including: a nonvolatile memory device including a plurality of memory cells; and a controller including an internal buffer including zone buffers, and configured to: allocate a plurality of zones to a storage space, select two or more erase units to be allocated to each zone based on a zone map table, fixedly and sequentially manage logical addresses of data written in the plurality of zones, based on reads for sequential logical addresses being requested by the external host device, read first data corresponding to the sequential logical addresses from the nonvolatile memory device, and output the first data to the external host device, and based on the reads being requested, perform a prefetch operation by reading second data corresponding to next sequential logical addresses, and storing the second data in the internal buffer, without receiving a next read request from the external host device.