Directory Cluster Allocation in Recording Media for Performance
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Solution Overview
Problem
In recording media like SD cards and CFexpress cards, frequent rewriting of data smaller than the block unit leads to degraded writing performance, especially for real-time data like moving images, due to the need to erase and rewrite entire blocks, resulting in capacity loss when directories are recorded in allocation units.
Innovation Solution
A control apparatus that allocates a cluster in the tail end area of the recording medium, which is not managed by the recording management unit, as a directory cluster, allowing directories to be recorded without reducing capacity efficiency by utilizing unused areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If directories are recorded in AUs (blocks) to ensure writing performance for real-time data, then writing performance is improved, but capacity loss occurs because the AU cannot be used for data recording
Solution Approach 1:
The recording medium is divided into two distinct management areas: a first area managed by the recording management unit for real-time data recording, and a second area managed by the cluster management unit for directory storage. This segmentation allows directories to be stored without occupying AUs needed for high-speed data recording, resolving the contradiction between writing performance and storage capacity.
Solution Approach 2:
The directory storage function is extracted from the AU management system and placed in a separate cluster management area. By taking out directory recording from the AU-based recording management unit, the patent eliminates the conflict where directories occupy AUs that could otherwise be used for high-speed data recording.
2Quantity of substance
If clusters in the tail end area are allocated to directories, then capacity efficiency is improved by utilizing unused areas, but directory recording must avoid managed areas to maintain writing performance
Solution Approach 1:
The patent segments the recording medium into a first area for real-time data recording and a second area for directory storage. The cluster management unit manages clusters in the second area, which includes tail end areas that would otherwise be unused. This segmentation enables efficient use of tail end space for directories without interfering with high-speed data recording in the first area.
Solution Approach 2:
Different areas of the recording medium are assigned different management qualities: the first area is optimized for high-speed data recording with AU-level management, while the second area (including tail end areas) is optimized for directory storage with cluster-level management. This local differentiation allows each area to serve its specific purpose efficiently.
Data Source
AI summary
A control apparatus configured to record data in a recording medium includes a cluster management unit configured to manage clusters in a predetermined area in a recording area of the recording medium, a recording management unit configured to manage clusters in the predetermined area in recording units each having a predetermined size larger than each cluster size, and a directory cluster allocation unit configured to set a cluster in the predetermined area to a directory cluster in which a directory is recorded. The directory cluster allocation unit is configured to allocate a cluster out of clusters in a tail end area in the predetermined area to the directory cluster, the clusters in the tail end area being smaller than a size of the recording units having the predetermined size and being not managed by the recording management unit.