Optical Disc Directory Cache for Reduced Seek Time
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical disc access systems face inefficiencies in accessing file systems due to longer seek times and increased latency, particularly when handling game content with numerous small files and high-density recording layers, which can impact the real-timeliness of game performance and increase the load on the drive system.
Innovation Solution
A disc access apparatus and method that cache directory information on a higher-read-rate medium, allowing the processor to reference this cached information to determine file positions on the disc medium without accessing the disc, thereby reducing the need for frequent layer jumps and motor adjustments, and enabling efficient data reading from the appropriate layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If directory information is read from the optical disc for every file access, then the file position can be obtained, but the access time increases due to seek time and reading latency
Solution Approach 1:
The patent applies preliminary action by reading and caching directory information from the optical disc into system memory before file access operations. This pre-loading of directory data eliminates the need for repeated disc seeks during file access, thereby reducing access time and improving file access speed without sacrificing accuracy in position determination
2Quantity of substance
If the optical disc uses multiple recording layers to increase capacity, then storage density improves, but the motor load increases due to frequent depth of focus adjustments
Solution Approach 1:
The patent introduces system memory as an intermediary layer between the multi-layer optical disc and the file access operations. By caching directory information that contains positional data for files across multiple layers, the system reduces the frequency of depth of focus adjustments and layer switching, thereby maintaining high storage capacity while significantly reducing motor load and energy consumption
3Adaptability or versatility
If game applications access multiple small files randomly, then game content can be loaded, but seek time increases due to random access patterns
Solution Approach 1:
The patent applies preliminary action by pre-reading the entire directory structure into system memory before game execution. This allows the game application to access multiple small files randomly without incurring seek time penalties, as all directory information is already available in memory. The random access flexibility is maintained while eliminating the time loss associated with physical disc seeking
Data Source
AI summary
The directory information on a file system recorded on an optical disc is cached onto a hard disk as a directory table. When accessing a file on the optical disc, a processor references the directory table so as to obtain information related to a position, on the disc medium, where the file to be accessed is located, without accessing the directory information on the optical disc. A disc I/O controller moves a pickup unit to the location indicated by the positional information on the file to be accessed and reads the data on the file. The pickup unit is used to detect signals from the optical disc.