Server-oriented operating systems tend to have certain features in common that make them more suitable for the server environment, such as
- GUI not available or optional
- bility to reconfigure and update both hardware and software to some extent without restart,
- advanced backup facilities to permit regular and frequent online backups of critical data,
- transparent data transfer between different volumes or devices,
- flexible and advanced networking capabilities,
- automation capabilities such as daemons in UNIX and services in Windows, and
- tight system security, with advanced user, resource, data, and memory protection.
Server-oriented operating systems can, in many cases, interact with hardware sensors to detect conditions such as overheating, processor and disk failure, and consequently alert an operator or take remedial measures itself.
Because servers must supply a restricted range of services to perhaps many users while a desktop computer must carry out a wide range of functions required by its user, the requirements of an operating system for a server are different from those of a desktop machine. While it is possible for an operating system to make a machine both provide services and respond quickly to the requirements of a user, it is usual to use different operating systems on servers and desktop machines. Some operating systems are supplied in both server and desktop versions with similar user interface.
The desktop versions of the Windows and Mac OS X operating systems are deployed on a minority of servers, as are some proprietary mainframe operating systems, such as z/OS. The dominant operating systems among servers are UNIX-based or open source kernel distributions, such as Linux (the kernel).
The rise of the microprocessor-based server was facilitated by the development of Unix to run on the x86 microprocessor architecture. The Microsoft Windows family of operating systems also runs on x86 hardware, and since Windows NT have been available in versions suitable for server use.
While the role of server and desktop operating systems remains distinct, improvements in the reliability of both hardware and operating systems have blurred the distinction between the two classes. Today, many desktop and server operating systems share similar code bases, differing mostly in configuration. The shift towards web applications and middleware platforms has also lessened the demand for specialist application servers.