In most cases, setting up Linux images on the mainframe hardware means setting up virtual hardware. In many cases, setting up virtual hardware is easier, more flexible, and cheaper than working with real hardware; for example, network setup can be easier because there is no need to install physical machines and cables. You can add and remove resources to meet your needs without having to commit new, extra hardware resources. Additionally, virtual over-configuration makes the environment flexible.
Redundancy can be configured into the LPAR and z/VM guests to allow for recovery from most hardware single points of failure. Hot-standby configurations are economically attractive.
If your company doesn't already have a predisposition toward a distributor, you will have the luxury of choosing the distributor based on what minimizes your need for making changes and getting the types of additional support you might need. The service contract should allow for the changes you plan to make.
The configuration capabilities of the mainframe, z/VM and Linux give you enormous advantage when you need to add extra virtual servers or resources, or if you need to try out new things. You can do so quickly, easily, and at no extra hardware cost. For example, you can create a new Linux server within minutes to try out some new software or idea.