This survey shows how much 16 of the largest and most popular social network sites have been unavailable during the first four months of 2008. How much has MySpace, Facebook, Friendster, Twitter, LiveJournal and many others been offline? Read on to find out.

The monitoring for this survey was done using the Uptrends uptime monitoring service.

We have included two tables, one with a summary of the downtime and uptime for the entire period, and another one which breaks down these numbers month by month.

Downtime summary, January through April

This table is sorted so that the highest downtime is at the top. In other words, it is one of the few lists where it is a good thing to be near the bottom.

* Pownce has only been monitored since January 22, when the site went public.

MySpace comes out on top, at least when it comes to website availability. Their website has only been unavailable for little over an hour so far this year. At the other end of the spectrum we find the Twitter website, which has been unavailable for more than 37 hours (a day and a half).

Orkut, Facebook, Classmates.com, Yahoo! 360, LiveJournal, Xanga and MySpace all have a 99.9% uptime or better so far in 2008, which has to be considered very good.

We also added Pownce for monitoring on January 22, when the site went public. Pownce is Kevin Rose’s post-Digg social networking site. (The other founders are Leah Culver, Daniel Burka and Shawn Allen.)

Downtime month by month

Since we thought it would also be interesting to have a look at the downtime numbers on a monthly basis, we have included a table for that as well. We have sorted the sites just as above, so the largest total downtime is at the top.

* Pownce has only been monitored since January 22.

This monthly view shows us that the majority of Twitter’s website problems were in January and February (it still had more than seven hours of downtime in April, though). Of course, Twitter also relies heavily on the use of SMS, but we did not monitor that aspect, only that the website responded (just as we did for all the other sites in this survey).

Friendster had the vast majority of its downtime in January, and has since then been very stable.

Bebo has, after a rocky January and February, stabilized their site significantly. AOL announced a deal with Bebo in March that it will acquire the social network for $850 million.

As we have mentioned in the pastp, all websites have downtime sooner or later. Social networks, by their very nature, will have a lot of visitors who return to the site frequently, and a lot of page views per visitor, so any downtime they have tends to be highly visible to their users. With many of these social networks counting their user base in the millions, it is a significant technical challenge for these sites to keep downtime to a minimum.