Acme Enterprises, a mid-size company with 1500 employees, has a strong e-commerce presence on the Internet. Their environment consists of several geographically dispersed web server farms and database servers. Several internally developed applications are employed on the web servers as content gateway interface (CGI) applications, providing interaction between user input and back-end database processing. .
Over the last 18 months, Acme has experienced significant growth in its online purchasing operations. Statistics collected over the eighteen-month period indicated a 33% increase in web site visitor traffic. The increased load is driven throughout the entire system thus affecting every part of Acme's web environment. Database transactions have experienced similar growth creating scaling issues equal to that of the front-end web servers.
To date, Acme has employed traditional scaling methods in an attempt to keep pace with increasing demands. These methods include the purchase and deployment of larger enterprise-class RISC processor servers, thereby scaling vertically. The concept of vertical scaling is readily apparent in the database back-end element of their architecture. Acme currently employs 2 Sun Fire 6800 servers, each with 24 processors and 64 gigabytes of memory. The front-end web server complex also consists of 30 mid-range Sun Fire 3800 servers, each with 8 processors and 8 gigabytes of memory. Acme's leadership has determined that the vertical scaling technique is now cost prohibitive. Each front-end web server, with the above configuration, has an estimated cost of $250,000. Citing several additional market factors including cost, Acme considers replacing or augmenting the front-end complex with the same class of servers as no longer feasible. However, recent scaling efforts in the back-end database infrastructure have successfully supplied a cushion for long-term growth, thereby rendering this element trouble-free.
