EVMS treats volumes and storage objects separately. A storage object does not automatically become a volume; it must be made into a volume.
Volumes are created from storage objects. Volumes are either EVMS native volumes or compatibility volumes. Compatibility volumes are intended to be compatible with a volume manager other than EVMS, such as the Linux LVM, MD, OS/2 or AIX. Compatibility volumes might have restrictions on what EVMS can do with them. EVMS native volumes have no such restrictions, but they can be used only by an EVMS equipped system. Volumes are mountable and can contain file systems.
EVMS native volumes contain EVMS-specific information to identify the name and minor number. After this volume information is applied, the volume is no longer fully backwards compatible with existing volume types.
Instead of adding EVMS metadata to an existing object, you can tell EVMS to make an object directly available as a volume. This type of volume is known as a compatibility volume. Using this method, the final product is fully backwards-compatible with the desired system.