Home > Mirror (computing)

1 Rationale

Mirroring of sites occurs for a variety of reasons:

• To protect data from a failure, usually in hardware. See disk mirror.
• To allow faster downloads for users at a specific geographical location. For example, a US server could be mirrored in Japan, allowing Japanese Internet users to download content faster from the local Japanese server than from the original American one. This may be viewed as caching on a worldwide scale.
• To counteract censorship and promote freedom of information. For example, an activist might post pictures on a website of a company conducting illegal activities or make available information on secret government activity and be litigated for such. Other internet users will make the content in question available on other servers when the legal action results in the cancellation of ISP or DNS services for the original activist.
• To provide access to otherwise unavailable information. For example, when the popular GoogleGoogle is a U. based search engine on the World Wide Web owned by Google Inc. Being the largest search engine on the web, Google receives at least 200 million (2 × 108) search requests per day through its website and client websites, such as AOL. In addit search engine was banned in 20022002 is a common year starting on Tuesday (see link for calendar). 2002 was the first palindromic year since 1991 and the last until 2112. 2002 was also designated: International Year of Ecotourism and Mountains National Science Year in the United Kingdom by the People's Republic of ChinaThe People's Republic of China PRC comprises most of the cultural, historic, and geographic area known as China. Since its founding in 1949, it has been led by the Communist Party of China (CPC). It is the world's most populous country, with a population, the mirror Elgoog was set up as a way of effectively circumventing the ban.
• To preserve historic content. Financial constraints may prevent the maintainers of a server from keeping older and unsupported content available to users who still may desire them - a mirror may be made to prevent this content from disappearing.
• To balance load. If one server is extremely popular a mirror may help relieve this load: for example if a LinuxThis article is about Linux-based operating systems, GNU/Linux, and related topics. See Linux kernel for the kernel itself. See Linux (washing powder) for the Swiss brand of washing powder. Tux, a plump penguin, is the official Linux mascot Linux is the n distribution is released as an ISO imageAn ISO image (as prescribed by ISO standard ISO 9660) is a file that represents a one-to-one copy of a specific computer filesystem, most widely used for the compact disc medium (i. e an entire CD or DVD-ROM). It is for this reason that many Linux, BSD, o onto the distribution developer's own server, this server may become overloaded with demand. Alternative download points allow the total number of download requests to be spread among several servers, maintaining the availability of the distribution.
• As a temporary measure to counterbalance a sudden, temporary increase in traffic. For example, slashdotted websites will often be mirrored by a few slashdotSlashdot (frequently abbreviated online as "/. is a popular technology-oriented weblog, primarily consisting of short summaries of stories on other websites with links to the stories, and provisions for readers to comment on the story. Each story generall posters until the article is pushed off the front page.
• To increase a site's ranking in a search engineGoogle search engine was mainly due to its powerful Pagerank algorithm and its simple, easy-to-use interface. A search engine is a program designed to help find files stored on a computer, for example a public server on the World Wide Web, or one's own co by placing hyperlinks from each mirror to every other mirror (a technique known as link farming). This is viewed as unethical by most search engine administrators and websurfers.
• Rarely, as a form of plagiarism. Usually pointless since a website popular enough to be worth plagiarizing will quickly discover the copy as soon as one of their many readers stumbles onto the plagiarized site.