Directory structure and performance (HPOFS)

High Performance Optical File System (HPOFS) volumes have a dual directory structure to access files. Both a hash and hierarchical structure exist to provide a primary and secondary path to the file data. If the primary directory structure becomes damaged, the secondary path is used.

The hash directory structure is designed to reduce the amount of media I/O required, which improves performance for file access. Because of this hash directory structure, directory depth has less effect on performance than if the directory were searched hierarchically. For example, if /DIRECTORY1 contains 1000 files and /DIRECTORY2 contains 100 files, file search times for files in /DIRECTORY1 will generally take no longer than file searches in /DIRECTORY2. This is because the system performs the searches by using the hash structure, not the hierarchical structure.

Directory depth has less effect on performance for a hash search than for a hierarchical search. However, the overall directory depths and total number of files on a volume will affect performance. In general, a volume with fewer files on it will result in better file performance than a volume with more files.