Between a Rock and a Hard Place!
Individual files in an HFS (Hierarchical File System) must always be accessed through
the OMVS kernel. Therefore, SMP/E is "OMVS aware":
Note that the modules required to run the OMVS kernel are loaded into
standard MVS load libraries. Most of the utilities used by OMVS users
are loaded into the HFS; there is a "permission bit" called the
"sticky bit" which indicates that the program should be fetched from
MVS libraries rather than the executable file in the HFS. This feature
is typically used for highly-used programs such as the OMVS shell,
which is the "startup program" for most users in the OMVS environment.
- a new HFS element type (++HFS) and HFS-associated MCS parameters
have been introduced. SMP/E understands OMVS permission bits.
- DDDEFs can point to directories within an HFS
- SMP/E incorporates a new utility used to load HFS objects, BPXCOPY
- to install maintenance into an HFS requires that an OMVS kernel
- anyone who needs to install maintenance into an HFS must be defined
as an OMVS "super user"
Good Housekeeping Note
Although the HFS containing the SMP/E target files must be "mounted"
(online and available to OMVS), you should not install maintenance
onto the running system. One method is to install maintenance into
an HFS that mirrors the structure of the production environment. This
HFS can be used as a test environment and then later swapped into the
production location. For fallback, you can swap the original HFS
SMP/E maintenance to HFS files often makes use of a "hard link" to define a copy
of an HFS file in an alternate location. This is similar to an alias in a PDS -
essentially, there are two pointers to the same file. However, extreme care is
required when attempting to rollin maintenance selectively on a file by file or
directory by directory basis. For more information, refer to
SMP/E and Hard Links
SMP/E at OS/390 V2R7 and up incorporates support for symbolic links.
While this type of link is more flexible, the existence of a symbolic
link does not guarantee the existence of the "real" HFS file.
Thus, you can have "orphan" symbolic links that point to a nonexistent
Speaking of Super Users
An OMVS user with uid=0 is a "super user". This means that they can
access any file in any HFS which is available to OMVS. In an OMVS
world, there is no distinction between the "super user" who installs
maintenance and the "super user" who administers the system. You may
wish to take this into account when planning your backup strategy.
SMP/E at OS/390 V2R7 and up allows a non-"super user" to install
maintenance into HFS (if authorized for BPX.SUPERUSER).
See Checking out Unix System Services Executables for information about finding
internal timestamps for programs stored in the HFS. See SMP/E for
more general information on SMP/E.