Architecture and Strategic Flexibility
So far, the vision of the N1 Grid has been presented. In addition, an extensive review of the many tasks that an organization must consider has been presented. Finally, there is a specific goal of strategic flexibility. With all that as background, the temptation is to move straight to an implementation design. That would be a mistake because architecture matters.
Although there is broad expertise in system design and implementation in the personnel that typically manage a data center, too often there is a limited focus on architecture. That is not an indictment against the IT operations staff. It is simply a result of typical daily operations. The architectural work used to develop most of the IT services in production is done outside of the data center. Data center personnel typically focus on only system design or implementation. Because the benefits of the N1 Grid are focused at the data center and a robust architecture is necessary for its success, it is important to articulate the difference between design and architecture.
Dot-Com & Beyond (Sun Professional Services) discusses the issue of design versus architecture as follows:
"The terms 'system architecture' and 'system design' are often used interchangeably, but in fact deal with two very different engineering processes.
In approaching the distinct but related tasks of architecture and design, it is important to remember this key principle: a system's design is constrained by its architecture. The system architecture establishes the big rules that must be followed by the system design (which in turn determines how the desired functionality should be realized by the system implementation). The process of architecture ends, and the process of design begins, when enough big rules have been established to ensure that as long as the design complies with those rules, the system will satisfy the established QoS requirements.
System architecture focuses primarily on the overall structure of a system, identifying major components and their relationships. The system architecture seeks to define:
How overall processing should be decomposed into component parts
How major components should be organized with respect to one another
How major types of operations, such as communication and storage, should be mechanized
Thus, the architect focuses on issues such as which components should communicate with one another, which should be visible to one another, and which should be replicated; how components should be distributed, how they should talk to one another, and where they should be stored."
Although the N1 Grid system design, and ultimately its implementation, is vitally important, an architecture must precede that design. As stated, the architecture, focused on the goal of strategic flexibility, strives to set the "big rules" by which the end design is guided. Through a process of decomposition, followed by organization, and finally mechanization, a valid architecture comes to life. That architecture, the fundamental and unifying system structure for the N1 Grid, is the primary focus of the remaining chapters in this part of the book.
However, before focusing on the specifics of the first component of the N1 Grid architecture, a review of the development of that architecture is presented. This development uses the SunToneSM Architecture Methodology (SunTone AM) to focus on the key business drivers and the near term business return on investment (ROI) that is necessary to achieve strategic flexibility. Finally, the functional requirements, backed up by use cases, provide the specifics of the N1 Grid architecture.