Flash Memory Snapshot via Address Conversion Table
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Solution Overview
Problem
Conventional semiconductor memory systems with flash memory struggle to effectively implement a snapshot function, leading to inefficient data management and increased loads on the controller, as they cannot simultaneously access and utilize both updated and previous data efficiently, and the address conversion process burdens the recording medium controller.
Innovation Solution
A storage system with a memory controller that manages flash memory by using an address conversion table and page status register to differentiate between latest, outdated, invalid, and unwritten data, allowing selective output of data based on logical addresses and reducing the load on the controller through efficient data storage and retrieval processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If update data is written without overwriting changing target data in flash memory, then data before and after updating temporarily coexist enabling snapshot function, but the memory part storing data before updating is treated as invalid and access is inhibited from outside
Solution Approach 1:
The patent introduces an address conversion table as an intermediary layer between the host computer and the flash memory. This table stores the correspondence between logical addresses and physical addresses, enabling the host to access snapshot data through logical addresses without directly interacting with the complex memory management internals. The address conversion table mediates the access control, allowing legitimate access to snapshot data while maintaining the invalidation mechanism for memory management purposes.
Solution Approach 2:
The patent segments the flash memory into multiple blocks, where each block can independently store either current data or snapshot data. This segmentation allows the system to maintain multiple versions of data (before and after updates) in different blocks simultaneously. The memory controller manages these blocks independently, enabling selective access to snapshot data while maintaining data integrity and allowing the snapshot function to coexist with normal write operations.
2Adaptability or versatility
If a recording medium controller writes past and current contents of data file to manage addresses, then snapshot function is enabled, but address conversion increases loads on the recording medium controller
Solution Approach 1:
The patent performs preliminary actions by pre-establishing the address conversion table that maps logical addresses to physical addresses before actual data access occurs. When snapshot data is written to flash memory, the system proactively updates the address conversion table with the new physical locations. This preliminary setup eliminates the need for complex real-time address resolution during data access, significantly reducing the processing load on the memory controller during normal operations.
Solution Approach 2:
The patent creates a copy of the address mapping information in the address conversion table, separating the complex physical address management from the simple logical address interface. Instead of performing complex address conversions during each data access operation, the system copies and stores the address mappings in advance, allowing the controller to simply lookup pre-computed addresses rather than performing intensive conversion calculations during data operations.
Data Source
AI summary
In a semiconductor memory computer equipped with a flash memory, use of backed-up data is enabled. The semiconductor memory computer includes an address conversion table for detecting physical addresses of at least two pages storing data by designating a logical address from one of logical addresses to be designated by a reading request. The semiconductor memory computer includes a page status register for detecting one page status allocated to each page, and page statuses to be detected include the at least following four statuses: (1) a latest data storage status, (2) a not latest data storage status, (3) an invalid data storage status, and (4) an unwritten status. By using the address conversion table and the page status register, at least two data s (latest data and past data) can be read for one designated logical address from a host computer.