Cold File Metadata Compression for Flash Free Space Reclamation
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Solution Overview
Problem
The frequent execution of garbage collection in non-volatile memory devices due to insufficient free space leads to performance degradation and reduced lifespan, particularly when write operations are performed.
Innovation Solution
A method is implemented to compress metadata of cold files in non-volatile memory, securing additional free space by storing compressed data in unused areas, thereby reducing the need for garbage collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If garbage collection is performed frequently to secure free space in non-volatile memory, then free space is maintained, but performance deteriorates and device lifespan is reduced
Solution Approach 1:
The patent applies data compression to metadata of cold files, changing the physical state of data from uncompressed to compressed form. This reduces the space occupied by metadata without affecting its functional properties, thereby securing free space without requiring garbage collection operations that would degrade performance
Solution Approach 2:
The patent creates a compressed copy of the metadata in the same storage location, replacing the original uncompressed metadata. This copy has the same functional properties (readability, integrity) but occupies less physical space, effectively increasing free space without data loss or performance impact
2Quantity of substance
If garbage collection is performed frequently to secure free space, then free space is maintained, but the number of garbage collection operations increases
Solution Approach 1:
The patent performs compression of cold file metadata in advance, before free space becomes critically low. This preliminary action secures free space proactively, preventing the need for frequent reactive garbage collection operations and reducing the frequency of such operations over time
Solution Approach 2:
The system uses its own stored data (cold file metadata) to generate free space through compression, rather than requiring external garbage collection operations. The compressed data serves the dual purpose of maintaining functionality while providing free space, making the system self-sufficient
3Quantity of substance
If compression is applied to all data, then free space is maximized, but compression overhead and processing time increase
Solution Approach 1:
The patent applies compression selectively to specific data categories (cold file metadata) rather than all data in the system. Cold files are identified by their access patterns and compressed accordingly, while hot files and active data remain uncompressed. This localized approach maximizes free space from compressible data while minimizing the processing overhead associated with compressing all data
Solution Approach 2:
The patent applies compression only to the extent necessary to secure adequate free space, rather than compressing all possible data. The system monitors free space levels and applies compression to cold file metadata only when needed, avoiding unnecessary compression operations and their associated processing overhead
Data Source
AI summary
Disclosed is an electronic device comprising: a non-volatile memory configured to store at least one file including metadata and user data; a file system configured to manage the at least one file through a log stream; and a file system (FS) manager configured to monitor a free space log included in the log stream corresponding to a first free space of the non-volatile memory, and to transmit a compression request to the file system based on the size of the first free space, displayed on the free space log, having a value less than a first reference value. The file system may be configured to: based on the compression request being received, compress at least a part of the metadata stored in the non-volatile memory based on the log stream, to store same in the first free space; and display a second free space of the non-volatile memory, secured through the compression of the at least a part of the metadata, as a reserved block log in the log stream.