A Server is a computer designed to process requests and deliver data to another computer over the internet or a local network.
The word “server” is understood by most to mean a web server where web pages can be accessed over the internet through a client like a web browser. However, there are several kinds of servers and even local ones like file servers that store data within an intranet network.
Although any computer running special software can function as a server, the most typical use of the word references the very large, high-powered machines that function as the pumps pushing and pulling data from the internet.
Most computer networks support one or more servers that handle specialized tasks. As a rule, the larger the network – in terms of clients that connect to it or the amount of data that it moves – the more likely it is that several servers play a role, each dedicated to a specific purpose.
Strictly speaking, the “server” is the software that handles a certain task. However, the powerful hardware that supports this software is also usually called a server because server software coordinating a network of hundreds or thousands of clients requires hardware much more robust than what you’d buy for ordinary consumer use.
Common Types of Servers
While some are dedicated servers where the server operates one function only, some implementations might use one server for multiple purposes.
A large, general-purpose network supporting a medium-sized company will likely deploy several different types of servers:
Web Servers
Web servers show pages and run apps through web browsers.
The server your browser is connected to right now is a web server that’s delivering this page, any images you might see, etc. The client program, in this case, is most likely a browser like Internet Explorer, Chrome, Firefox, Opera, Safari, etc.
Web servers are used for all sorts of things in addition to delivering simple text and images, like for uploading and backing up files online through a cloud storage service or online backup services.
Email Servers
Email servers facilitate the sending and receiving of email messages.
If you have an email client on your computer, the software is connecting to an IMAP or POP email server to download your messages to your computer, and an SMTP server to send messages back through the email server.
FTP Server
FTP servers support the moving of files through File Transfer Protocol tools.
FTP servers are accessible remotely via FTP client programs.
Identity Server
Identity servers support logins and security roles for authorized users.
Hundreds of different types of specialized server types support computer networks. Apart from the common corporate types, home users often interface with online game servers, chat servers, audio streaming services, etc.
Network Server Types
Many networks on the internet employ a client-server networking model integrating websites and communication services.
An alternative model called peer-to-peer networking allows all devices on a network to function as either a server or client on an as-needed basis.
Peer networks offer a greater degree of privacy because communication between computers is more targeted, but most implementations of peer-to-peer networking aren’t robust enough to support very large traffic spikes.
Server Clusters
The word cluster is used broadly in computer networking to refer to implementations of shared computing resources. Typically, a cluster integrates the resources of two or more computing devices that could otherwise function separately for some common purpose (often a workstation or server devices).
A web server farm is a collection of networked web servers, each with access to content on the same site that functions as a cluster, conceptually.
However, purists debate the technical classification of a server farm as a cluster, depending on the details of the hardware and software configuration.
In a computer, data storage is the place where data is held in an electromagnetic or optical form for access by a computer processor.
Storage is frequently used to describe the devices and data connected to the computer through input/output (I/O) operations — that is, hard disk and tape systems and other forms of storage that don’t include computer memory and other in-computer storage.
For the enterprise, the options for this kind of storage are of a much greater variety and expense than those related to memory.
Storage hierarchy
Enterprise data storage is often classified as primary and secondary storage, depending on how the data is used and what type of media it is placed on.
Primary storage holds data in memory (sometimes called random access memory or RAM) and other built-in devices, such as the processor’s L1 cache. Secondary storage commonly includes data on hard disks, tapes and other devices requiring I/O operations. Secondary storage media is often used in cloud storage.
Primary storage is much faster to access than secondary storage because of the proximity of the storage to the processor and the nature of the storage devices. On the other hand, secondary storage can hold much more data than primary storage.
Antiquated terms for primary and secondary storage are main storage and auxiliary storage, respectively. To add to the confusion, there is an additional meaning for primary storage that distinguishes actively used storage from backup storage.
Types of storage
There are many types of data storage, with various levels of capacity and speed. These include magnetic tape; magnetic disks; optical discs, such as CDs, DVDs and Blu-ray disks; flash memory; main memory (dynamic RAM); and cache memory.
Capacity requirements
Data storage capacity requirements tell users how much storage is needed to run an application, a set of applications or data sets. Capacity requirements take into account the types of data. For instance, simple documents may only require KBs of capacity, while graphic-intensive files, such as digital photographs, may take up MBs, and a video file can require GBs of storage. Computer applications commonly list minimum and recommended capacity requirements to run.