4. MEASUREMENT RESULTS
In this section, we first show the number of users downloading
or seeding on BitTorrent/Suprnova. Then we
present detailed performance measurements of the availability,
the integrity, the flashcrowd effect, and the download
performance of the system.
4.1. Overall system activity
The number of users over time on BitTorrent/Suprnova
gives a good indication of both the general performance
and the dynamics of the system. We show the popularity
of BitTorrent/Suprnova in terms of the number of downloads
over time and its dependence on technical failures
in the system.
Figure 1 shows the total number of downloads, and the
number of downloads of three types of content (games,
movies, and music) in progress in BitTorrent around
Christmas 2003. We have selected this month for presentation
because it shows a large variance in the number of
downloads due to several BitTorrent/Suprnova failures.
The lowest and highest number of downloads in Figure 1
are 237,500 (on Christmas day) and 576,500 (on January
9). Our HTML script requests every hour all pages from
one of the active Suprnova mirrors. The consecutive data
points have been connected with a line when there was
no overall systems failure.