When most people talk about servers, they envision huge, humming boxes, quite unlike normal PCs, that have computing and storage power well above everyday needs. Here are a couple of definitions of “server”:
- “a software program, or the computer on which that program runs, that provides a specific kind of service to client software”, http://www.linfo.org/server.html
- “a computer that provides services used by other computers”, http://cplus.about.com/od/glossar1/g/serverdefn.htm
The first of those definitions is the key: software can also function as a server for client programs on the same computer. Another way of looking at it also reveals a big difference – physical shape and space. A common format for servers is the blade server. These are devices which have all the functionality of normal servers but use a modular (often pizza-box-shaped) design to reduce space and energy consumption – and to stack tens, even hundreds of them into racks.
Servers are used for specialized purposes for the most part rather than being general-purpose computers like PCs. Good examples of servers would be mechanisms for file sharing, print servers, proxy servers (acting as an intermediary for others), game servers, fax servers, communications server, even a home server.
The whole internet is based on this client-server model, with millions of servers operating simultaneously, such as the Domain Name system, which translates website names into IP addresses; the World Wide Web – the system of interlinked hypertext documents; and e-mail servers. In a nutshell, any common usage of web resources involves a server (host) and a client.
A server OS and server applications are needed to connect the different parts of a system and ensure there is no battle for resources and no problems with running it. A simple analogy is that to operate a printer you have to install the necessary drivers. Moving beyond this simple explanation, different servers must fulfill various operations: a university server should provide students with access to scholarly databases while an e-commerce one must have the ability to handle millions of credit card transactions to meet customer demands. To satisfy these roles, servers need specific server software and applications, which “serves data to client software” on request. http://www.ehow.com/facts_7234638_server-software_.html
The task of selecting a good server OS largely depends on the hardware available, the software system requirements, the databases and programming languages already present, budget limitations, and the main purpose of the server. The three most used OSs are:
- Linux, a specialized variant of Unix, which is growing in popularity because of its flexibility and open source nature
- Windows Server variants, with a more stringent support model (which also costs more), and which offer different versions depending on business size and needs.
- Unix, in various varieties paid and free, which is perhaps the oldest and most ‘established’ solution.
A comprehensive list of server applications includes:
- Proxy servers
- Mail and Groupware Servers
- Web servers
- Real-Time Communication Servers
- FTP (File Transfer Protocol) Servers
- Collaboration Servers
- List Servers
- Telnet Servers
- Web Servers
- Fax Servers
- File and Print Servers
Examples of Server program packages in practice:
How can seemingly expensive server software (for example, Google’s Search Appliance for midlevel business costs upwards of $30,000 http://www.actualmetrics.com/compare/google-search-appliance/google-mini/) improve business operations, and increase productivity and profitability? Let’s take a look at some alternatives and business case studies.
- The Google Search Appliance offers businesses the power of its search algorithms for their own databases or websites. According to its website, the server appliance will “improve customer satisfaction”, “increase employee productivity”, consume “minimal administration time”, and “provide filtered search results”. Amongst their clients are Reuters, BP, the American Red Cross, mtcss, and Essilor. But was it a worthwhile investment?
- British Petroleum(BP) was faced with an ineffective server search engine, which caused dissatisfaction among employees, business relations, and customers. The company network consisted of 1250+ websites which offered irrelevant search results and turned away many potential customers. By adopting this server software, the company “increased user search interactions by 80%”, “reduced headcount needed to support search”, and most importantly “delivered accurate search results”. http://static.googleusercontent.com/external_content/untrusted_dlcp/www.google.com/bg//enterprise/pdf/case_studies/gsa/gsa_case_study_bp.pdf
- “Windows Server 2008 R2” has “a robust set of features”, among which are virtualization with Hyper-V, virtualizing the system resources of your physical computer; Remote Desktop Services; Power and Server Management for time and energy efficiency; Scalability and Reliability. Example Microsoft users are Target Corporation, Union Pacific, EmpireCLS Worldwide, Lifetime products and hi5 Networks. http://www.microsoft.com/en-us/server-cloud/windows-server/2008-r2-features.aspx
- Union Pacific – a freight railroad company - planned to virtualize 500 Windows-based servers to decrease IT expenditure and request response time. Because its previous Linux technology caused problems with the Windows server group and most of the staff were used to the Windows OS, “Server 2008 R2” with Hyper-V virtualization was a good solution.
- VMware with its free vSphere Hypervisor, formerly known as ESXi, is the most widely used virtualization tool, http://www.v-index.com/ . Its hypervisor architecture is not dependent on a general purpose operating system, making it independent. Because of its free nature and seamless upgrade feature, it is a good starting point for small and medium businesses which have not decided on a virtualization vendor and/or have a tight budget.
- IBM’s quite recent PureSystems aim to provide a complete experience – a bundled architecture which combines storage, server, networking and management in one. Its motto is “convert technology expertise into reusable, downloadable packages” and the software also supports cloud. The software focuses on pre-configured applications to make the user experiences faster and easier. It includes an infrastructure system PureFlex and a platform system PureApplication.
- The FreeRADIUS.org project offers a free-of-charge Remote Authentication Dial-In Service Server, which has authentication, authorization and accounting functions. It is one of the most widely used RADIUS applications and is open source, so computer experts can make their own customizations. Although it is a Unix based-software, a Windows version, albeit a bit older, can be found at FreeRADIUS.net.
- Kaspersky is a server solution which deals with unwanted and spam e-mail. This is one aspect of general IT security and a strong pain point for users. Kaspersky deals with it by “utilizing list-based filtering, rules-based filtering, signature filtering and linguistic heuristics”. The server program doesn’t require a powerful machine and comes at a reasonable price.
By no means exhaustive, this list is meant to provide examples of the breadth and width of server software. Note that the main functions running throughout all server applications are good resource usage, online security and the ability to handle a heavy transaction load.