Each volume group must have a unique name. No two volumes groups in an Oracle FS System can have the same name.
The total number of volume groups is limited to 5000.
The system allows up to 10 volume groups nested in a parent volume group.
Volume groups allow you to group logical storage objects that reside in different Storage Domains.
When deleting a volume group any nested objects, such as child volume groups, or LUNs, will be deleted also.
You can use volume groups to organize the storage objects that parallel your organizational structure. For example, you might want to group all of your LUNs that are located in the United States in one volume group, and the LUNs for the European sites in another volume group.
If you do not create nested volume groups, create all volumes within the default volume group to create a broad, shallow hierarchy.
Figure 1: Default volume group example
Create nested volume group by creating a parent volume group, and then assign logical volumes or other volume groups to the parent volume group.
Figure 2: Nested volume groups