5. FILES › 5.5 USS File System Information Area File › 5.5.1 USS Directory Entry File (HFSDIR) › 5.5.1.3 HFSDIR Usage Considerations

5.5.1.3 HFSDIR Usage Considerations

This section identifies any special considerations or
techniques related to using the HFSDIR file.

Relationship to Data Sources from VCC

HFSDIR is built from the data in the USS catalog and contains
observations for all files and directories for the mounted
file systems that are scanned.  The HFS scan is different
from the VCC scan in which all data sets residing on the
selected volume are scanned.  A volume may contain many file
systems but HFS scan scans only those file systems that are
mounted at the time the scan is started.

An example of the basic information provided for every file
or directory in each observation is the space allocated in
blocks (DIRBLKSA).  The space allocated in blocks is the
space used by the file or directory.  At the file system
level, the total space allocated is reserved when the file
system is created but only a portion of that file system may
be used.  The actual space is utilized by the individual
files or directories that are created in the file system.
The allocated but unused space would not be used for
accounting purposes as it is not occupied by any file or
directory.  For this reason and the fact that only mounted
systems are represented in HFSDIR file, we strongly
discourage the use of this file for accounting.  The existing
VCADAA file contains a single record for each file system
data set (mounted and unmounted) reflecting all space
allocated.

Since all files and directories of the file systems are
scanned, the information lends itself to detail analysis of
the individual file and/or directory as well as the entire
file system.