When you image a physical rack, the software in the manifest bundle is loaded onto the physical rack.

In a multi-rack environment, you can either image all racks in parallel, or image rack 1 first followed by the other racks one at a time. To image multiple racks in parallel, you need a vSphere Distributed Switch and VIA VM for each rack.

Figure 1. VIA Setup for Parallel Imaging of Multiple Physical Racks
multirack