Server (computing)

Designating a computer as "server-class hardware" implies that it is specialized for running servers on it.

In computing, "server" dates at least to RFC 5 (1969),[5] one of the earliest documents describing ARPANET (the predecessor of Internet), and is contrasted with "user", distinguishing two types of host: "server-host" and "user-host".

The use of "serving" also dates to early documents, such as RFC 4,[6] contrasting "serving-host" with "using-host".

In the publish-subscribe pattern, clients register with a pub-sub server, subscribing to specified types of messages; this initial registration may be done by request-response.

There are exceptions that do not use dedicated servers; for example, peer-to-peer file sharing and some implementations of telephony (e.g. pre-Microsoft Skype).

Since servers are usually accessed over a network, many run unattended without a computer monitor or input device, audio hardware and USB interfaces.

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.

They will often be able to be configured, powered up and down, or rebooted remotely, using out-of-band management, typically based on IPMI.

Modern data centers are now often built of very large clusters of much simpler servers,[15] 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.

[17] The main beneficiaries of so-called "server on the go" technology include network managers, software or database developers, training centers, military personnel, law enforcement, forensics, emergency relief groups, and service organizations.

Proprietary operating systems such as z/OS and macOS Server are also deployed, but in much smaller numbers.

[21][needs update] One estimate is that total energy consumption for information and communications technology saves more than 5 times its carbon footprint[22] in the rest of the economy by increasing efficiency.