Many private BitTorrent communities employ Sharing Ratio Enforcement
(SRE) schemes to incentivize users to contribute. It has been demonstrated
that users in private communities are highly dedicated and that they seed much
longer than users in communities where SRE is not employed. While most pre-
vious studies focus on showing the positive effect of user dedication in achieving
high download speed, in this paper we explore the user behaviors in private
communities, we argue the reasons for these behaviors, and we demonstrate
both the positive and the negative effects of these behaviors. We show that
under SRE, users seed for excessively long times to maintain required sharing
ratios, but that their seedings are often not very productive (in terms of low
upload speed) and that their long seeding times do not necessarily lead to large
upload amounts. We find that as users evolve in the community, some users
become more committed, in terms of increasing ratios between their seeding
and leeching times. In the mean time, some users game the system by keeping
risky and low sharing ratios while leeching more often than seeding. Based on
these observations, we analyze strategies that alleviate the negative effects of
these user behaviors from both the user’s and the community administrator’s
perspective.@en