How Universal Volume Manager works

When you map to a volume in an external storage system, it becomes an internal volume in the local storage system.

• A local system port must be connected to the external storage system port with a Fibre Channel cable. This route between ports is the external path.

• The external volume is represented in the local storage system 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. External port is an attribute assigned to ports on the local storage system.

You can connect multiple external storage systems to one external port even if the external port is already in use.

 Only hosts that are connected to the local storage system can access and copy mapped external volumes.

You can create LDEVs in two different ways:

• By using Universal Volume Manager during mapping

• By using the Virtual LVI/LUN (VLL) function after mapping

In this case, the internal volume (the internal volume to which an external volume is mapped) is the virtual device (VDEV) and the LDEV in the external volume is the LDEV.

As shown in the figure above, you must have LDEVs in the mapped external volumes for use in the local system.