Patch Dependencies

A patch that depends on other software in order to install or run correctly is said to have a dependency on that other software. In order to become fully active, a patch may require changes to areas of the system other than those it modifies. Such a patch may have a documented dependency on one or more patches or nonpatch software products that are responsible for the changes in these other areas.

For example, in Figure 3-3: “Patch Supersession Chains and Patch Dependencies”, patch PHXX_33662 depends on patch PHXX_32384, and patch PHXX_43826 depends on PHXX_33662. Patches PHXX_31967 and PHXX_31937 depend on each other (mutual dependency).

Figure 3-3 Patch Supersession Chains and Patch Dependencies

Because HP-UX patches are cumulative, a patch satisfies all the dependencies that all of its superseded patches satisfy. The opposite is not true, however. A superseded patch does not satisfy a dependency on a superseding patch. Figure 3-3: “Patch Supersession Chains and Patch Dependencies” provides an example. Patch PHXX_33662 requires patch PHXX_32384, but PHXX_43826 can also satisfy this requirement because it supersedes PHXX_32384. However, patch PHXX_32384 does not satisfy PHXX_43826's dependency on PHXX_33662.

For more information about supersession, see “Ancestors and Supersession”.

Types of Dependencies

HP provides patch dependency information for a patch in its patch details page and its patch text file. The dependency information is contained in the following fields:

Patch Dependencies
Patches that are required for proper operation.
Other Dependencies
Various dependencies that cannot be described as patch dependencies, such as those that are needed only under specific circumstances.




	NOTE: While looking at a patch details page or a patch text file, you might notice an additional field that is dependency related. The Hardware Dependencies field represents a different type of dependency than those presented in this section. It does not show dependencies on other patches, but rather gives specific system models to which a patch is limited.

Corequisites and Prerequisites

The following is a list of the most common dependency requisite types:

A corequisite is a dependency in which one fileset requires that another fileset be installed or configured at the same time. For example, if fileset A requires that fileset B be installed at the same time, fileset B is a corequisite for fileset A.
A prerequisite is a dependency in which one fileset requires another fileset to be installed or configured before the first fileset can be installed or configured. For example, fileset C may require that fileset D be installed before fileset C can be installed. Therefore, fileset D is a prerequisite for fileset C.

Advanced Topic: Determining Corequisite and Prerequisite Filesets with the swlist Command

You can use the following command to determine the dependent filesets. Replace dependency_type with either corequisite or prerequisite, as appropriate.

swlist -vl fileset -a dependency_type fileset

For example:

$ swlist -vl fileset -a corequisite PHSS_29964.DCEC-ENG-A-MAN
# Initializing...
# Contacting target "some_system"...
#  PHSS_29964.DCEC-ENG-A-MAN
fileset
corequisites PHCO_24400.CORE-SHLIBS,fa=HP-UX_B.11.11_32/64

Enforced and Unenforced (Manual) Dependencies

A patch's dependency upon another patch will either be enforced or unenforced by SD-UX. Starting with HP-UX 11i v1 (B.11.11), SD-UX install commands supported the use of requisites for automatically enforcing dependencies. Prior to HP-UX 11i v1, users had to maintain dependencies manually.

Enforced dependencies
Dependencies that are registered using corequisite or prerequisite attributes and managed by SD-UX.
Unenforced dependencies (also known as manual dependencies)
Dependencies that SD-UX does not register as requisites and thus cannot enforce when performing patch installation. You can identify these types of dependencies by checking the manual_dependency category tag. The user must ensure that the required patches are installed to satisfy these manual dependencies.

Impact of Dependencies on Acquiring Patches

HP strongly recommends that you use the ITRC as your primary source for acquiring patches. If you acquire individual patches using the ITRC's Patch Database, the patches required to meet the dependencies of these patches are automatically selected for download along with the patches you selected manually. The analysis performed by the Patch Database to select these patches takes into account supersession and patch warnings. Unless you have a specific reason to do otherwise, you should download these automatically selected patches along with the patches you explicitly selected. This automatic selection of patches represents one of the many time-saving features provided by the ITRC.

For a description of how to identify and acquire the additional patches that may be needed to satisfy dependencies, see “Advanced Topic: Checking for All Patch Dependencies”.




	NOTE: If you download patches from sources other than the ITRC, such as an HP FTP server, you are completely responsible for identifying and downloading the patches required to satisfy all dependencies.

Standard HP-UX patch bundles, such as the Quality Pack, do not require users to perform any dependency analysis. All patches required to satisfy all dependencies are included in the bundles. Using standard HP-UX patch bundles increases confidence that you have obtained and installed all necessary patches to satisfy all dependencies.

Patch Dependencies

Technical documentation

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Types of Dependencies

Corequisites and Prerequisites

Advanced Topic: Determining Corequisite and Prerequisite Filesets with the swlist Command

Enforced and Unenforced (Manual) Dependencies

Impact of Dependencies on Acquiring Patches