Modern enterprise data centers must support a large group of divergent users. These include internal workers, remote employees and sites, suppliers, partners, and customers. Mid-sized enterprises rarely have the resources to support separate data center infrastructures for each client type. A single data center with either physical or logical infrastructure tiers can provide isolation, security, and performance for all users. The data center can be organized into multiple logical tiers. These can be defined as four primary levels:
- Perimeter tier for remote access to the data center.
- Presentation tier offering the user interface or presentation applications.
- Application tier where the primary enterprise applications reside.
- Back-end tier supporting the database and storage facilities.
While a physical separation of these different structures is ideal, the reality is that all but the largest data centers will integrate one or more of these into a single physical structure and use logical partitioning to provide the separation between them. Recognize the risks and benefits to define the structure that best fits the business requirements of the enterprise.