Storage Controller Active Zone Refresh to Reduce Garbage Collection
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Solution Overview
Problem
Non-volatile memory devices experience reduced lifetime due to frequent garbage collection operations, leading to decreased available storage capacity and increased power consumption, especially when managing data in a random access manner.
Innovation Solution
Implementing a storage controller that performs an active zone refresh operation, where zones are managed sequentially, allowing data to be stored in a power loss protection block instead of the original block when a power-off request is received, thus maintaining sequential write operations and reducing block waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If random access storage management is used, then data accessibility is improved, but garbage collection operations increase frequency
Solution Approach 1:
The storage device is divided into multiple zones (first zone, second zone, third zone) with different access patterns. The first zone uses random access for high-speed data accessibility, while the second and third zones use sequential access to minimize garbage collection operations. This segmentation allows the system to achieve both fast data access and reduced garbage collection frequency by routing different types of data to appropriate zones.
2Productivity
If large over provisioning region is allocated for garbage collection, then garbage collection efficiency is improved, but available storage capacity decreases
Solution Approach 1:
The storage capacity is segmented into user data zones (first, second, third zones) and a separate power loss protection zone. By dividing the storage structure, the system can perform garbage collection in dedicated areas without consuming into the user data zones, thereby maintaining available storage capacity while still enabling efficient garbage collection operations in the PLP zone.
Solution Approach 2:
The power loss protection zone acts as an intermediary area for garbage collection operations. Instead of performing garbage collection directly in the user data zones, the system uses the PLP zone as a buffer and intermediate storage area, allowing garbage collection to proceed efficiently without reducing the capacity available for user data.
3Productivity
If sequential zone-based storage is used, then garbage collection frequency is reduced, but data access flexibility decreases
Solution Approach 1:
The storage device is segmented into multiple zones with different access characteristics. The first zone supports random access for flexible data operations, while the second and third zones use sequential access to reduce garbage collection frequency. This multi-zone segmentation allows the system to provide both sequential storage benefits and random access flexibility depending on the specific data access requirements.
Solution Approach 2:
The storage device provides universal access methods by supporting both random access (through the first zone) and sequential access (through the second and third zones). This multi-functionality allows the system to adapt to different data access patterns and workloads, maintaining data access flexibility while benefiting from reduced garbage collection frequency in sequential zones.
4Loss of energy
If power-off operations are performed during write requests, then power consumption is reduced, but data integrity may be compromised
Solution Approach 1:
The system performs preliminary actions by maintaining a power loss protection zone that is prepared in advance to receive data. When a power-off request occurs during a write operation, the system can complete the data transfer to the pre-configured PLP zone, ensuring data integrity. This preliminary setup of the PLP zone allows safe power-off operations without compromising data integrity.
Solution Approach 2:
The power loss protection zone serves as an intermediary buffer that protects data during power interruptions. When power is interrupted during a write request, the data is transferred to this intermediary PLP zone, which is specifically designed to handle such scenarios. This intermediary structure ensures data integrity is maintained even when power-off operations occur during write requests.
Data Source
AI summary
Disclosed is a method of operating a storage controller which communicates with a host and a non-volatile memory device. The method includes receiving a first state transition request for a device open from the host, performing a first active zone refresh operation of the non-volatile memory device in response to the first state transition request such that a zone, which has an active state before an immediately previous power-off is processed to a sequentially writable state in one block, receiving, by a first buffer memory, first target data to be stored in a first block of a first zone among the plurality of zones from the host depending on a first write request, receiving a first power-off request from the host, during processing the first write request, and storing the first target data in a first power loss protection (PLP) block of the non-volatile memory device.