The database tier runs on approximately 50 servers and consists of SQL Server 7.0 databases containing product, customer, support, and order data. Dell uses the replication feature of SQL Server 7.0 to decrease the time required for database maintenance and improve performance for front-line Web servers. When databases are being updated, there's no need to take them offline or perform bulk copies of data at low-traffic times. Dell implements the presentation and business logic layers logically, rather than physically, on the same servers. For example, Web servers run both the presentation and business logic needed to handle Web requests.
Commerce servers run both the presentation and business logic needed to handle commerce requests.
This parallel architecture gives Dell performance and stability. If one object has a problem, we can take out just the affected server without affecting the others. WLBS and NLB balance traffic as incoming Web requests feed through many front-end PowerEdge servers. This scheme allows additional servers to be easily added without impacting online operations. They serve static HTML pages, which are displayed on the client side.