Directory Entries

On operating systems that ha ve the system directory cen tralized on one disc, access to directory services for ￿les on an y disc on the system requires serial access to the system directory. In other words, they must occur one at a time. A t peak usage times, this creates a bottleneck due to physical contention for one disc and logical con tention for one directory user.

The space for the directory structure is spread across the v olume set, not necessarily located on one volume. The locking mechanism allows multiple readers and ensures that the proper locks for speci￿c c hanges in the directory structure, suc h as ￿le name insertions and deletions.

MPE/iX uses directory en tries that are spread across all mem bers of the system v olume set to speed up ￿le access and eliminate the ph ysical or logical serialization imposed b y a centralized directory.

With MPE/iX, eac h disc in a system v olume set has a directory of ￿les located on it. Th us, user requests automatically go through the directories and arriv e at the disc containing the requested ￿les without going through a cen tralized directory . Multiple users can simultaneously access a system directory .

On nonsystem volume sets, the directory is restricted to the MASTER v olume of the set, so that it is not necessary to moun t the entire set at one time.

Native Mode System Components

This section describes the MPE/iX operating system subsystems important for programming only in Native Mode (NM). F or programming information on MPE/iX operating in Compatibilit y Mode (CM), refer to the Migration Series of man uals. Fundamental Operating System (FOS) is the name for the MPE/iX operating system and associated softw are included in a standard 900 Series HP 3000 installation. The softw are that automatically comes with MPE/iX is a collection of high-lev el tools that mak e the system easier to use. In addition, other high-lev el tools are optionally a vailable for use with MPE/iX. Collectiv ely, these tools include:

MPE/iX operating system

Languages:

HP C/iX

COBOL II/XL

HP Pascal/iX

HP FORTRAN 77/iX

HP Business BASIC/V (CM only) SPL/V (CM only)

RPG/V (CM only)

Forms design and screen handling:

-forms control

-VPLUS/V (formatted data en try application)

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