SERVER OPERATING SYSTEM

Some popular operating systems for servers — such as FreeBSD, Solaris, and Linux — are derived from or are similar to UNIX. UNIX was originally a minicomputer operating system, and as servers gradually replaced traditional minicomputers, UNIX was a logical and efficient choice of operating system for the servers. UNIX-based systems, many of which are free in both senses, are the most popular.
Server-oriented operating systems tend to have certain features in common that make them more suitable for the server environment, such as
an optional or absent GUI,
ability to reconfigure both hardware and software to some extent without restart,
advanced backup facilities to permit online backups of critical data at regular and frequent intervals,
transparent data transfer between different volumes or devices,
flexible and advanced networking capabilities,
automation capabilities like 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 and/or take remedial measures itself.
Because the requirements of servers are, in some cases, almost diametrically opposed to those of desktop computers,[citation needed] it is extremely difficult to design an operating system that handles both environments well; thus, operating systems that are well suited to the desktop may not be ideal for servers and vice versa. Regardless of OS vendor, system configurations that are ideal for servers may be unsatisfactory for desktop use, and configurations that perform well on the desktop may leave much to be desired on servers. This results in many operating systems' release in both server and desktop versions. Nevertheless, 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 and open source kernel distributions.[citation needed]
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 versions beginning with Windows NT have incorporated features that making them suitable for use as server operating systems.
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.