HP 3000 Manuals

New Features of MPE/iX: Using the Hierarchical File System

Hierarchical File System (HFS) 

This section compares the traditional MPE file system with the enhanced
MPE hierarchical file system (HFS).

MPE/iX file system 

Prior to Release 4.5, the MPE/iX file system includes accounts, groups,
and files.  This is the traditional MPE file system structure that you
are used to.

Figure 2-1  shows an example of two accounts on an MPE/iX system:  the
SYS and ACCT1 accounts.  The SYS account contains the PUB and GRP1
groups.  The groups PUB and GRP1 coexist as equals.  GRP1 cannot be a
subgroup of PUB or vice versa.  The ACCT1 account has only one group,
also called PUB. Files exist within the groups.  The files cannot be
located directly under the accounts.  They can only exist in groups.


          Figure 2-1.  MPE/iX File System (Prior to Release 4.5) 

MPE/iX hierarchical file system 

Beginning with MPE/iX Release 4.5, the file system structure of MPE/iX is
enhanced with the introduction of the MPE/iX hierarchical directory
structure.  This was accomplished by integrating the MPE/iX HFS structure
within and around the traditional MPE file system.  This provides the
benefits of both structures to MPE/iX users without forcing them to
choose one environment or the other.

MPE/iX hierarchical directory services present an integrated view of the
file system.  All file system components exist under one directory called
the root directory (designated as /).  Directories are structures that
can contain files and other directories.

MPE/iX accounts and groups are considered to be special directories that
serve as hierarchical directories while continuing to serve as
traditional MPE accounts and groups.  To ensure that the classic MPE file
system view still exists, accounts can only be created under the root
directory, and groups can only be created under accounts.

Figure 2-2  shows the MPE/iX file system structure introduced as of
Release 4.5.  In the figure, the boxed portion shows how the traditional
account, group, and file system structure fits into the HFS structure.
Notice that hierarchical directories and HFS files can now fall under
traditional MPE groups.  For example, the figure shows lowercase_file as
being located in the PUB group of the ACCT1 account.  Also notice that
the directory dir3 falls under the GRP1 group in the SYS account.  The
traditional MPE accounts, groups, and files can and do coexist with the
HFS files and directories.  As the figure shows, as of Release 5.0, files
and directories can exist under accounts.


          Figure 2-2.  MPE/iX File System (Release 4.5 and Later) 

Although accounts and groups are directories, they maintain their unique
characteristics as well.  This manual still refers to accounts and groups
where necessary for clarity.  When discussing characteristics of
directories in general (including accounts and groups), this manual uses
the term "directory." When referring specifically to a directory that
exists outside of the traditional account-group structure, this manual
uses the term "HFS directory."

MPE/iX 5.0 Documentation