Digg effect aka Slashdot effect happens 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. 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 Digg effect. In this post I will list number of options to test your website readiness for Digg effect, find the weak points and then fix it.

Server response time test

Check how long does it take for your server to respond to request with host-tracker.com. It pings your site from multiple locations around the world and gives you detailed report.

The ideal response time for a website ready for Digg effect would be in range 0.2-0.3 sec. If it’s more than 1 sec, your website will experience problem with Digg effect.

Fail safe test

This is the very close to reality way to test your site for Digg effect.

loadimpact.com will help you to run for free simple load tests with up to 50 concurrent, simulated users. Which is a good way to start, you can also pay $9/day to test your site with up to 5,000 users.

If your graph is stable and not going up with increased number of concurrent users, your website will be ok with Digg effect.

Page load speed test

These tools will help you to make sure your website pages load is fast enough for end users:

Your YSlow score should be at least 80.
Google Page Speed is similar Firefox addon to test the speed of the website load.
site-perf.com provides you with fast and accurate evaluation of website load and its weak points.
tools.pingdom.com is similar service to evaluate page load time.

Digg effect mitigation

Despite your best efforts to get ready for Digg effect, the website fails under the siege of multiple Diggers. You can try to mitigate the effect by temporarily redirecting requests for the targeted pages to one of these mirrors.

A website can be accessed through the Coral Cache by adding .nyud.net to the hostname in the site’s URL. For example, http://example.com becomes http://example.com.nyud.net. The Coral caching system does not rewrite embedded links to images, so is useful only for sites using relative links to images.

Rorr.im is a Digg content mirror. When a story is made popular, the rorr.im bot immediately attempts to make a copy of the site. If the site is brought down by the Digg Effect, a copy of the content is still available.