BitTorrent’s Long Tail Alive and Well on Private Torrent Sites

Bollywood, wrestling, anime, B-movies, art-house cinema, Asian action flicks and porn, lots and lots of porn — whatever you’re into, there’s bound to be a private torrent tracker for it somewhere. These private BitTorrent communities often work by invitation only and try to stay under the radar of both rights holders and the downloading masses. But does this exclusive approach to online piracy really work?

That’s the question three French researchers are trying to answer. Sylvain Dejean, Thierry Penard and Raphaël Suire from the University of Rennes infiltrated 42 private torrent trackers to figure out what made them tick. The trio published the results of its work in a new study titled “Olson’s Paradox Revisited: An Empirical Analysis of File-sharing Behavior in P2P Communities,” and the paper is good news for long-tail proponents and file-sharing enthusiasts alike.

Mention BitTorrent, and most people automatically think of The Pirate Bay, with its high-profile court case and 20 million concurrent active users. Many administrators of private torrent trackers probably couldn’t be happier about this, because it helps them to stay under the radar. There are hundreds of private and specialized trackers out there. Some restrict new memberships to invited users, while others stick to a certain number of maximum users and only open up registrations when old and inactive accounts have been purged from their databases.

Private trackers also tend to enforce a share ratio, meaning that you have to upload a certain amount of data for every gigabyte you download. Some are more lenient and just warn users that don’t contribute enough. Other sites restrict the download of new torrents to users with a certain ratio, and some even kick you out if you don’t contribute. The effectiveness of those ratios has actually been a point of contention for some time. Torrent site admins tend to believe that ratios help to keep free-riders out. BitTorrent inventor Bram Cohen, on the other hand, argued a while back that ratios just provoke cheating and that the way some administrators enforce sharing through ratios is “extremely destructive.”

The French study doesn’t go that far, but it does make clear that ratios can be counterproductive. Sites with ratios tend to get more people to share files, but the number of files shared is lower than on less-restrictive sites. From the study: “[T]he easiest way to rapidly increase the share ratio is to share a content which is highly requested. As a consequence, shared sources are concentrated on few files and limit the extend of the catalog.”

This doesn’t mean that big, open sites without any regulations at all work better than private communities. The key seems to be that private communities serve certain niches of the long tail. “Specialized communities seem…to encourage voluntary contribution,” the researchers found. Topical sites just work better than general interest platforms, and the right balance of rules and access controls can help to foster these niche communities.

Those findings are in stark contrast to a study about music on file-sharing networks that came out last month. The authors of that study argued that file sharers only swap a few select popular titles and largely ignore the long tail. However, the long tail seems to be alive and well in private communities.

And no, this is not just a question of the size of a site. “The individual incentives to contribute voluntary tend to decrease with the size of a P2P community,” the study reads. “However, the collective contributions tend to increase as the community size rises.” Private BitTorrent trackers don’t gravitate towards a small selection of popular content when their audience grows, but actually offer a larger catalog of highly available files.

In other words, BitTorrent does indeed have a long tail. You may just need an invitation to access it.