The Operating System

An operating system is the underlying software that issues commands to the computer's hardware. It handles such functions as:

• Allocating storage space

• Scheduling tasks

• Acting as an interface to the user's computer when an application is running

Web sites are constantly putting further demands on the operating system of the server. It is therefore important to select an operating system that is flexible, can protect itself from multiple server processes competing for system resources, and is able to support essential server-side processes such as application servers and search engines. All the while, the operating system must continue to perform well.

Certainly performance is a critical factor in the selection of an operating system, but you also should consider other factors. In determining which operating system best meets your needs, you should be mindful of the following criteria:

• Scalability/flexibility. Can it scale to a platform that is capable of accommodating large traffic loads? Is it flexible enough to work with a variety of Internet services? How many CPUs can it handle?

• Network management. Can it support common IP network management applications? Does it integrate with your existing network environments and directory services?

• Application availability. Can it run the applications you run today? Are new applications being developed for it? How much do the applications that you need cost?

• Management. Does it provide flexible, accessible management utilities?

• Cost. What are the costs for related hardware, the operating system itself, and any required server software? Is the operating system so complex that it will require additional spending for specialized personnel to install and maintain the system?

• Performance. How many users can you support with a single machine? Does the operating system support symmetric multiprocessing (SMP)? Does it let you balance loads across multiple systems?

• Application development. Are the development tools you use available for the platform? Are there standard operating system services and industry-standard interfaces to support development?

• Reliability. Does it support RAID or clustering? Can you hot-swap components?