Rootvg WPARs
A system WPAR which is configured with its own root volume group on one or more dedicated storage devices is called a rootvg WPAR. Configuring a rootvg WPAR gives the WPAR administrator complete control over managing the storage devices exported to the WPAR, the volume groups on those devices, and the logical volumes and file systems within those volume groups. A system WPAR which is not a rootvg WPAR does not have its own root volume group, but has file systems created in logical volumes created out of the root volume group of the global system.
For a rootvg WPAR, storage devices must be exported (or allocated) to the WPAR when it is created. After it has been created, the chwpar command can be used to allocate additional disks to the WPARs root volume group or, if it contains multiple disks, to deallocate a disk from the WPARs root volume group. It is not possible to change a WPAR without its own root volume group into a rootvg WPAR after it has been created.
Rootvg WPARs can be configured to support live application mobility when used in combination with IBM® PowerVM® Workload Partitions Manager for AIX®.
A configuration with a WPAR owned root volume group (a RootVG WPAR) helps to isolate the file systems and volume groups of a WPAR from the global system.
Rootvg WPAR mobility considerations
A WPAR whose file systems are all NFS mounted or all SAN based is eligible for Live Application Mobility, wherein a workload running in a WPAR on one LPAR might be moved to another compatible LPAR and execution resumed at the same point. This relocation of a WPAR involves moving its executable code to the target LPAR, while keeping the application data on the same storage devices. Thus, the storage devices containing the file systems must be visible and accessible from both LPARs.A typical configuration might include two SAN based disks containing the rootvg of the WPAR, with a third SAN based disk exported to the WPAR and containing a separate volume group with application data. This gives the WPAR administrator complete control over creating new file systems or resizing the existing file systems within those volume groups. If the intent is to be able to relocate the WPAR, the WPAR Manager can be used to create the WPAR, as well as to move it between LPARs.