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Main category: "Servers (computing)
The purpose of a server is to share data as well as to share "resources and distribute work. A server computer can serve its own computer programs as well; depending on the scenario, this could be part of a "quid pro quo transaction, or simply a technical possibility. The following table shows several scenarios in which a server is used.
||Hosts "web apps (computer programs that run inside a "web browser) allowing users in the network to run and use them, without having to install a copy on their own computers. Unlike what the name might imply, these servers need not be part of the "world wide web; any "local network would do.
||Computers with a web browser
||Maintains an index or table of contents of information that can be found across a large distributed network, such as computers, users, files shared on file servers, and web apps. "Directory servers and "name servers are examples of catalog servers.
||Any computer program that needs to find something on the network, such a "Domain member attempting to log in, an "email client looking for an email address, or a user looking for a file
||Maintains an environment needed for one communication endpoint (user or devices) to find other endpoints and communicate with them. It may or may not include a directory of communication endpoints and a presence detection service, depending on the openness and security parameters of the network
||Communication endpoints (users or devices)
||Shares vast amounts of computing resources, especially "CPU and "random-access memory, over a network.
||Any computer program that needs more CPU power and RAM than a personal computer can probably afford. The client must be a networked computer; otherwise, there would be no client–server model.
||Maintains and shares any form of "database (organized collections of data with predefined properties that may be displayed in a table) over a network.
||"Spreadsheets, "accounting software, "asset management software or virtually any computer program that consumes well-organized data, especially in large volumes
||Shares one or more "fax machines over a network, thus eliminating the hassle of physical access
||Any fax sender or recipient
||Shares "files and "folder, storage space to hold files and folders, or both, over a network
||Networked computers are the intended clients, even though local programs can be clients
||Enables several computers or gaming devices to play "multiplayer games
||Personal computers or "gaming consoles
||Makes "email communication possible in the same way that a "post office makes "snail mail communication possible
||Senders and recipients of email
||Shares "digital video or "digital audio over a network through "media streaming (transmitting content in a way that portions received can be watched or listened as they arrive, as opposed downloading a whole huge file and then using it)
||User-attended personal computers equipped with a monitor and a speaker
||Shares one or more "printers over a network, thus eliminating the hassle of physical access
||Computers in need of printing something
||Enables computer programs of a computer to play sound and record sound, individually or cooperatively
||Computer programs of the same computer
||Acts as an "intermediary between a client and a server, accepting incoming traffic from the client and sending it to the server. Reasons for doing so includes content control and filtering, improving traffic performance, preventing unauthorized network access or simply routing the traffic over a large and complex network.
||Any networked computer
||Hosts "web pages. A web server is what makes "world wide web possible. Each "website has one or more web servers.
||Computers with a web browser
Almost the entire structure of the "Internet is based upon a "client–server model. High-level "root nameservers, "DNS, and routers direct the traffic on the internet. There are millions of servers connected to the Internet, running continuously throughout the world and virtually every action taken by an ordinary "Internet user requires one or more interactions with one or more server. There are exceptions that do not use dedicated servers; for example "peer-to-peer file sharing, some implementations of "telephony (e.g. pre-Microsoft "Skype).
A rack-mountable server with the top cover removed to reveal internal components
"Hardware requirement for servers vary widely, depending on the server's purpose and its software.
Since servers are usually accessed over a network, many run unattended without a "computer monitor or input device, audio hardware and "USB interfaces. Many servers do not have a "graphical user interface (GUI). They are configured and managed remotely. Remote management include "MMC, "SSH or a "web browser.
Large traditional single servers would need to be run for long periods without interruption. "Availability would have to be very high, making hardware reliability and durability extremely important. "Mission-critical enterprise servers would be very "fault tolerant and use specialized hardware with low "failure rates in order to maximize "uptime. "Uninterruptible power supplies might be incorporated to insure against power failure. Servers typically include hardware "redundancy such as dual "power supplies, "RAID "disk systems, and "ECC memory, along with extensive "pre-boot memory testing and verification. Critical components might be "hot swappable, allowing technicians to replace them on the running server without shutting it down, and to guard against overheating, servers might have more powerful fans or use "water cooling. They will often be able to be configured, powered up and down or rebooted remotely, using "out-of-band management, typically based on "IPMI. Server casings are usually "flat and wide, and designed to be "rack-mounted.
These types of servers are often housed in dedicated "data centers. These will normally have very stable power and Internet and increased security. Noise is also less of a concern, but power consumption and heat output can be a serious issue. Server rooms are equipped with air conditioning devices.
A server farm or server cluster is a collection of computer servers maintained by an organization to supply server functionality far beyond the capability of a single device. Modern "data centers are now often built of very large clusters of much simpler servers, and there is a collaborative effort, "Open Compute Project around this concept.
A class of small specialist servers called "network appliances are generally at the low end of the scale, often being smaller than common desktop computers.
Sun's "Cobalt Qube
3; a computer "server appliance
(2002); running Cobalt Linux (a customized version of Red Hat Linux, using the 2.2 Linux kernel), complete with the Apache web server.
On the Internet the dominant operating systems among servers are UNIX-like "open source "distributions, such as those based on "Linux and "FreeBSD, with "Windows Server also having a very significant share. Proprietary operating systems such as "z/OS and "macOS Server are also deployed, but in much smaller numbers.
Specialist server-oriented operating systems have traditionally had features such as:
- "GUI not available or optional
- Ability 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
- Tight system security, with advanced user, resource, data, and memory protection.
- Advanced detection and alerting on conditions such as overheating, processor and disk failure.
In practice, today many desktop and server operating systems share similar "code bases, differing mostly in configuration.
In 2010, data centers (servers, cooling, and other electrical infrastructure) were responsible for 1.1-1.5% of electrical energy consumption worldwide and 1.7-2.2% in the United States. One estimate is that total energy consumption for information and communications technology saves more than 5 times its "carbon footprint in the rest of the economy by enabling efficiency.
- ^ Windows Server Administration Fundamentals. Microsoft Official Academic Course. 111 River Street, Hoboken, NJ 07030: "John Wiley & Sons. 2011. pp. 2–3. "ISBN "978-0-470-90182-3.
- ^ Comer, Douglas E.; Stevens, David L. (1993). Vol III: Client-Server Programming and Applications. Internetworking with TCP/IP. Department of Computer Sciences, Purdue University, West Lafayette, IN 479: "Prentice Hall. pp. 11d. "ISBN "0-13-474222-2.
- ^ Richard A. Henle, Boris W. Kuvshinoff, C. M. Kuvshinoff (1992). Desktop computers: in perspective. Oxford University Press. p. 417.
Server is a fairly recent computer networking term derived from queuing theory.
- ^ "Rulifson, Jeff (June 1969). DEL. "IETF. RFC 5. https://tools.ietf.org/html/rfc5. Retrieved 30 November 2013.
- ^ Shapiro, Elmer B. (March 1969). Network Timetable. "IETF. RFC 4. https://tools.ietf.org/html/rfc4. Retrieved 30 November 2013.
- ^ Using the HTTP Publish-Subscribe Server, Oracle
- ^ "Web Servers". IT Business Edge. Retrieved July 31, 2013.
- ^ Li, Huang, Shen, Chu (2010). ""A Realistic Evaluation of Memory Hardware Errors and Software System Susceptibility". Usenix Annual Tech Conference 2010" (PDF). Retrieved 2017-01-30.
- ^ "Google uncloaks once-secret server". CNET. CBS Interactive. Retrieved 2017-01-30.
- ^ "Usage statistics and market share of Linux for websites". Retrieved 18 Jan 2013.
- ^ "Server Oriented Operating System". Retrieved 2010-05-25.
- ^ Markoff, John (31 Jul 2011). "Data Centers Using Less Power Than Forecast, Report Says". "NY Times. Retrieved 18 Jan 2013.
- ^ "SMART 2020: Enabling the low carbon economy in the information age" (PDF). "The Climate Group. 6 Oct 2008. Retrieved 18 Jan 2013.
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