Only on December 23, 2003 there was a problem with the tracker for a few minutes, which is not visible in
the Supernova data. The results from the Peer ping script
show a significantly lower number of downloads, which
is due to the firewall problem (40 % of the peers were
firewalled). The gaps in the Peer ping results were due to
disk quota problems on the DAS, which ran our measurement
software. From the measurements we conclude that
the global BitTorrent/Supernova components are capable
of efficiently handling very large flash crowds. Also, because
of the strong sudden increase in the number of
download ers, it is clear that the arrival process is not Poisson.
4.5. Download performance
In this section, we examine the efficiency (download
speed) and the effectiveness (number of available files)
of downloading.
Figure 6 presents the results of a two-week experiment
in which the average download band width of 54,845