UNIX SOFTWARE MANAGEMENT

Software management is (...) a challenge. This spans control over the installation of applications, middleware, and system-software patches that sit on top of the operating system. Administrators typically have to contend with a continuous cycle of updates in these areas, as well as a stream of customizations that address particular issues. Several functions can help to simplify this task, including,

• Software Registry: a central repository for configuration data related to hardware, the operating system, and applications that is manipulated and searched with database-like queries, instead of the traditional UNIX /etc files for system information and “dot files” in users’ home directories.
• Software Version Control and Patch Management Tools, i.e., a rigorous mechanism to keep track of which versions of applications are installed on the system, and which patches to system software have been applied.
• Two-phase Commit for Patch Installation, in which the patch management mechanism allows automatic roll-backs if an installation of software or a patch causes problems to the system, in which case administrators can fully back out of installations, restoring the system to its original state.

Tru64 UNIX uses a hybrid approach for registering software-configuration information, in which the traditional /etc files remain in place, but the system accesses them via a single, consistent framework (internally known as MCL) that contains component definitions for each file and how it can be read and modified. The MCL creates a common data model that cleanly maps to (and can be exported) to Simple Network Management Protocol (SNMP) MIBs. This model can also be exported in future releases to LDAP directories and the Common Information Model (CIM) of the cross-platform Web Based Enterprise Management (WBEM) initiative. MCL provides a structured but user-interface independent set of APIs to be used for building management tools in past, present, and future user-interface paradigms. This piece of the framework is known as the Sysman User Interface Toolkit, or SUIT, and all Compaq’s UNIX system management tools are built on top of it. Because the MCL/SUIT approach maintains the existence of /etc files that are familiar to traditional UNIX administrators, it allows new system-management methodologies to develop while preserving old capabilities.

While all of the studied systems provide standard procedures for installing patches to the base operating system, AIX, HP-UX, and Tru64 UNIX have a slight advantage over competitors due to their ability to allow patches to be installed using two-phase commits. AIX gives administrators the option to apply an update, and then reject or commit to it after testing. The mechanism can be used with licensed options, patches, and any installable application software. Tru64 UNIX provides a tool called dupatch for managing patches. This tool allows administrators to keep preexisting code around, so that patches can be backed out if necessary. HP’s Software Distributor (SD-UX) allows patches to be in applied status (i.e., they can be rolled back), committed (cannot be rolled back) or superseded. The other systems do not provide formal mechanisms allowing system administrators to back out of patches by automatically restoring software to its preexisting state if necessary.