LinuxTracker, Torrent Seeding and Your Client

by John Coombe

BitTorrent files, colloquially torrents, are the most popular method of sharing files among people all over the Internet now because it is true peer to peer sharing. The servers do not host any files, only the identifying files called tracking files. These are used to enable the servers to keep track of who has what part of which file and to allocate priorities to the packets being sent.

The LinuxTracker site serves huge numbers of distros' torrents and is not exclusively for the use of PCLinuxOS. Because of the large numbers of torrents that are active at any given time, it is not uncommon for individual BT clients to not be able to connect to the tracker sometimes due to the amount of traffic that the site encounters 24/7 x 52 weeks/year.

Usually, if you go back and look at your BT client an hour or two later, it will likely show something different.

An example of what is happening at the LinuxTracker (from bottom of main page) - this changes all the time
Tracking 2,673 Torrents with 237,110 Peers (84,505 Seeders and 152,605 Leechers)
Current Seeder/Leecher Ratio (%) = 55%
Total Registered Users 25,080
Members Online (Now): 13 Members
Members Online (In last 24 Hours): 312 Members
Most Users Online: 594 Members on: 2007-04-20 08:15:41

So you can see it is not uncommon for several thousand torrents to be active at any given time and just look at the numbers of seeds/leeches. All of them have to communicate with LinuxTracker. Due to this fact, it is normal that the SiteAdmin of this tracker (and others) sets the time that the tracker sends out an update request to each peer to around an hour. If the update request was made more frequent than once an hour, the amount of network bandwidth would be humongous, and he would have to pay for that. Also, if it was made more frequent, it could act like a DOS (denial of service) for the site. This aspect of busy sites is well known. There are some sites where the update request has been set at 2 hours to reduce traffic.

If, due to the amount of traffic collisions, an individual BT client misses getting the update request, then you may have to wait for another hour for it to happen again. It does not mean all the seeds/leeches have vanished, it just means your BT client missed the last update request.

Of course, this is for a torrent that is still active and has a lot of peers using it and so lots of traffic. Eventually everyone downloads the file(s) and has finished leeching. So all the seeds stop bothering to continue to seed. Sometimes a torrent becomes what is called a dead torrent, and if you try to download (leech), you fail unless a seed is kind enough to restart for you! When a seed is 'dead' no matter how long you wait, it will stay dead. Even if you get an update request from the tracker you will never be able to connect to another peer because there are not any left. When a torrent is dead, it is dead. :-(

A snapshot look at the torrent statistics at the LinuxTracker site shows: 4712 completed 368 seeds 132 leeches. Another snapshot look in 5, 15, or 30 minutes would show the number of seeds/leeches higher or lower, depending on the traffic during that time.

I hope that gives some sort of concept as to what is happening.