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The Slashdot effect, also known as slashdotting, occurs when a popular website links to a smaller site, causing a massive increase in traffic. This overloads the smaller site, causing it to slow down or even temporarily close. The name stems from the huge influx of web traffic that results from the technology news site Slashdot linking to websites. The effect has been associated with other websites or metablogs such as Fark, Drudge Report and Digg, leading to terms such as being Farked or Drudged and the Digg effect. Typically, less robust sites are unable to cope with the huge increase in traffic and become unavailable – common causes are lack of sufficient data bandwidth, servers that fail to cope with the high number of requests, and traffic quotas. Sites that are maintained on shared hosting services often fail when confronted with the Slashdot effect.
Links from other popular websites can cause problems comparable to this effect – see traffic overload.
Sites such as Slashdot, Digg, and Fark consist of brief submitted stories and a self-moderated discussion on each story. The typical submission introduces a news item or website of interest by linking to it. In response, large masses of readers tend to simultaneously rush to view the referenced sites. The ensuing flood of page requests from readers can exceed the site's available bandwidth or the ability of its servers to respond, and render the site temporarily unreachable.
One comment on a Slashdot story humorously summarized the effect: "Slashdot is world famous. A roving random distributed denial of service attack before which web, network and systems administrators alike quake and have terrible nightmares about."
Major news sites or corporate websites are typically engineered to serve large numbers of requests and therefore do not normally exhibit this effect. Websites that fall victim may be hosted on home servers, offer large images or movie files or have inefficiently generated dynamic content (e.g. many database hits for every web hit even if all web hits are requesting the same page). These websites often become unavailable within a few minutes of a story's appearance, even before any comments have been posted. Occasionally, paying Slashdot subscribers (who have access to stories before non-paying users) have rendered a site unavailable even before the story is posted for the general readership.
Few definitive numbers exist regarding the precise magnitude of the Slashdot effect, but estimates put the peak of the mass influx of page requests at anywhere from several hundred to several thousand hits per minute. The flood usually peaks when the article is at the top of the site's front page and gradually subsides as the story is superseded by newer items. Traffic usually remains at elevated levels until the article is pushed off the front page, which can take from 12 to 18 hours after its initial posting. However, some articles have significantly longer lifetimes due to the popularity, newsworthiness, or interest in the linked article; an example is the case of an announcement of Windows 2000 and Windows NT 4 source code leaks.
Some have recently commented that the Slashdot effect has been diminishing. 
When the targeted website has a community-based structure, the term can also refer to the secondary effect of having a large group of new users suddenly set up accounts and start to participate in the community. While in some cases this has been considered a good thing, in others it is viewed with disdain by the prior members, as quite often the sheer number of new people brings many of the unwanted aspects of Slashdot along with it, such as trolling, vandalism, and newbie-like behavior.
Assistance and prevention
Slashdot does not mirror the sites it links to on its own servers, nor does it endorse a third party solution. Mirroring of content may constitute a breach of copyright and, in many cases, cause ad revenue to be lost for the targeted site. The questionable legality of the practice is one of the primary reasons that Slashdot has not implemented mirroring.
One tool commonly advocated to assist smaller sites in bearing the load of a Slashdot effect is the Coral P2P Web Cache. The Coral caching system does not rewrite embedded links to pages or images, so is useful only for sites using relative links to images or other pages. Additionally, Coral will only serve content from the original site up to 24 hours after it becomes unreachable.
MirrorDot and Network Mirror are systems that automatically mirror any Slashdot-linked pages to ensure that the content remains available even if the original site becomes unresponsive. Rorr.im is a similar alternative for Digg users. Sites in the process of being Slashdotted may be able to mitigate the effect by temporarily redirecting requests for the targeted pages to one of these mirrors.
Notes and references
- Solution for Slashdot Effect? on Wired News
- Slashdot FAQ: What is the "Slashdot Effect?"
- A research paper describing strategies for handling the Slashdot Effectda:Slashdot-effekt