Hierarchical Directories; What Is A Hierarchy - HP 9000 200 Series Manual

Hierarchical Directories
A directory contains information about files, such as file name, size, and type.
In
hierarchical directory structures, a directory is itself a file, but it is used only to organize
and control access to other files. This section describes the two BASIC directory formats
that implement hierarchical directories:
• Hierarchical File System (HFS) format (used with HP-UX, some BASIC, and some
Pascal systems)
• Shared Resource Manager (SRM) format (the disc format is actually called Struc-
tured Directory Format, or SDF, on catalog listings of these directories). Note that
SRM system require an SRM controller and lets several workstations share a disc.
You cannot use HFS as a way of sharing a disc without needing a controller.
What Is a Hierarchy?
As the word "hierarchy" suggests, hierarchical directories are arranged in "levels." A
hierarchical directory may contain either files or other directories.
• A directory is "superior" to the files and directories it contains.
• A file or directory within a directory is said to be "subordinate" to the containing
directory.
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Figure 3-7. Hierarchy of Directories
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Mass Storage Concepts