How Universal Volume Manager works
A volume in an external storage system becomes an internal volume in VSP G200, G400, G600 when you map to it.
A local system port must be connected to the external storage system port with a fiber cable. This route between ports is the "external path".
The external volume is represented in the VSP G200, G400, G600 as an internal volume, and the path between them is the “mapping path”.
The figure below shows the connection between the local and external storage systems. In this figure, the external system is connected to the local system’s “external ports” via a switch using the Fibre-Channel interface. An “external port” is an attribute assigned to VSP G200, G400, G600 ports.
Multiple external storage systems can be connected to one external port. You can add an additional external storage system even when the external port is already in use.
Mapped external volumes must be accessed and copied only by hosts that are connected to the VSP G200, G400, G600, not by hosts connected to the external systems.
Logical devices (LDEVs) are created during or after the mapping operation. If created after mapping, the LDEVs are created in the same way they are when you create normal internal volumes using Virtual LUN. As shown in the figure, LDEVs in mapped external volumes are required for use in the local system.