Managing software with detached WPARs

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System WPARs exist in two basic forms as either shared or detached (non-shared /usr) workload partitions, though the file system characteristics can vary.

The shared form (shared /usr) of a system WPAR has the /usr file and the /opt file systems mounted from the global system hosting the WPAR. For shared system WPARs, all changes within the /usr file and the /opt file systems are immediately visible within the WPAR along with the installation files and information required to synchronize the non-shared (root) portion of the WPAR global system within the /usr file system. The syncwpar command will synchronize a shared WPAR with its global environment.

The detached form (non-shared /usr) of system WPAR has a separately installed writable /usr file and /opt file system. Detached WPARs provide improved flexibility by allowing the installation of different software in a WPAR than existing software in a shared WPAR environment. When it is necessary to have detached WPARs, you can use the syncwpar and inuwpar commands to manage the system software in detached WPARs and recover from situations where the WPAR has become incompatible with the global environment.

If you have WPARs on an AIX 6.1 operating system, and you migrate the global system to AIX 7.1 or AIX® 7.2, the software in the WPARs must also be migrated. The migwpar command migrates a WPAR from AIX 6.1 to AIX 7.1. The migwpar command can also be used to migrate a versioned WPAR from AIX 5.2 or AIX 5.3 to a native AIX 7.1 or AIX 7.2 WPAR. Starting with IBM® AIX 7.2 with Technology Level 2, you can enable versioned WPARs to remain functional (as versioned WPARs) after the global system is migrated to a new operating system level.

The syncwpar command cannot be used with AIX 5.2 or AIX 5.3 versioned WPARs. The software in versioned WPARs must be maintained separately from the global environment.

You can use shared WPARs unless it is required that the /usr file systems be writable within the WPAR. Detached WPARs increase administrative process usage due to the following unique operating environments:
  • Operating system updates applied in the global environment are not immediately available in a detached WPAR.
  • It is possible for the system software in a detached WPAR to become unusable and not boot if it is not compatible with the running kernel. This can happen simply by rejecting or applying updates in either the global environment or the WPAR, but not both.
  • Installation files used to populate the non-shared (root) portion of a fileset reside in a packaging directory in the shared environment, but the files used to populate the /usr file and the /opt file systems in a detached WPAR are only on installation media. Thus, it is difficult to duplicate software installation steps that were taken in the global environment in the detached WPAR.