The virtual data center architect must be able to take a holistic approach to data center design. This means that for every decision made, the architect must understand how the environment as a whole will be impacted.

An architect is required to be, at the very least, familiar with all aspects of the data center. They must understand how the different components of a data center, such as storage, networking, computing, security, and management, are interconnected, as shown in the following diagram:

It has become very important to understand how any decision or change will impact the rest of the design. Identifying dependencies becomes an important part of the design process. If a change is made to the network, how are computing, management, and storage resources affected? What other dependencies will this introduce in the design? Failing to take a holistic approach to design can result in unnecessary complications during the design process, and potentially costly fixes after the design is implemented.

The following scenario is built as an example which helps illustrate the concept of using a holistic design approach.

You have been engaged to design a virtualization solution for a financial organization. The solution you are proposing is to use 10 GB Converged Network Adapters (CNA) to provide connectivity to the organization's network in three 1U rack-mount servers. The organization needs to separate a Virtual Local Area Network (VLAN) that is currently configured to be delivered over the CNA onto a physically separate network to satisfy a new compliance requirement. A 1 GB network will provide sufficient bandwidth for this network, and the network should be highly available. Single points of failure should be minimized.

To support this compliance requirement, you, the architect, must take a holistic approach to the design and answer a number of questions about each design decision, for example:

1. Are there network ports available in the current rack-mount servers, or will a network card need to be added? If a card has to be added, are there Peripheral Component Interconnect (PCI) slots available?
2. Will a dual-port network card provide sufficient redundancy, or will the network need to be separated across physical cards? Are there onboard network ports available that can be used with a PCI network card to provide in-box redundancy?
3. Has the hardware for the physically separate switch been obtained? If not, how long before the equipment is received and deployed? Will this have an impact on the implementation schedule?
4. How will the virtual switch need to be configured to provide the connectivity and redundancy that is required?

The impact can be fairly significant, depending on some of the answers. For example, let's say the 1U rack-mount server will not support the required network adapters needed to satisfy the requirement and a different 2U rack-mount server must be used. This then raises more questions, such as whether there is sufficient space in the rack to support the new server footprint.

What if the requirement had been that the applications connected to this network be virtualized on separate physical server hardware and storage? What parts of the design would have to change? The architect must be able to understand the dependencies of each part of the design and how a change in one place may affect other areas of the design.

As you think through these questions, you should be able to see how a change to a requirement can have a deep impact on many other areas of the design. It becomes very important to identify requirements early on in the design process.