How can full torrent be snatched with only partial upload?

[josepheccleston]

Hi there,

I thought I knew how torrents worked, but now I'm completely confused. I created a brand new torrent with files totalling 5.75GB in size. As requested by the site, in the torrent I placed a private tracker generated by the website membership (each member has their own private tracker ID).

I then started the torrent, registered it at the website and updated the tracker, which it found and started working straight away. Before long I had 40 or so people leeching on the 1 seed I was providing.

I have a slow connection, so it was going to take a couple of days before I could upload the 5.75 GB in size to the group of people leeching it.

Now I understand that each leecher takes different parts of my file and it's redistributed within the group, but what I don't understand is that less that 24 hours later, my torrent was snatched (In total, around 50 snatchers and now further leechers)... YET... (and here's the bit I don't get), when I look at my utorrent entry, I can see that I've only uploaded a total of 2.3GB.

So how is it possible for the others to have snatched the full torrent if I (as being the original creator and seeder) have only managed to upload less than half of it?

[DreadWingKnight]

Is your torrent a re-pack of other files?

[josepheccleston]

Thank you for replying -

The torrent consists of a re-pack of files that could feasibly be found elsewhere (although not available on the site I provided it)... But it had the addition of an extra 'read-me' text (notepad) file that was written personally by me.

Is it possible that someone with better upload speeds, who had the same main files, could just download my .txt file, add his main files that are the same, and be a seeder too?

[DreadWingKnight]

Yup.

[jbebad]

Isn't the torrent file unique? only one of a kind? Statistics reported are at the torrent level - regardless of content. I could down load a torrent, check the files and notice that I already had some of the same name, do a force re-check and realize that I have already downloaded some (or all) of the files already. Then I would only need to download the missing(?) files, skip new the file(s) I don't want (such as your text file), or skip those files with the same name - because I already had them - but failed the force-recheck. If leecher skips files it could show completed - and it might be reported to a tracker that it was seeding - when in fact he did not get/download the entire torrent. It has been posted on this site many times where individuals download (or wanted to download) only a subset of the torrent. Once they have download that subset uTorrent marks it as completed - from the downloaders perspective it is. Is it now reported as completed to the tracker? From the initial seeders perspective it should not be - if he wants to quit uploading when a specific number of seeders is reached. A tracker would show it as completed because they want to inflate the availability of the torrent and get more seeders/leeches to use their site.

The ability of the client not taking into account data that was already download, skipped, or a re-added torrent can inflate statistics. For example, I download a torrent and I received most of the data. Then for some reason, I deleted the torrent from uTorrent. I re-add it. And since I have already download a some of data, I do a force-recheck. I have already download 90+% of the torrent. Now when I upload/seed it the ratio is based on the amount I have upload (since I have re-added the torrent) vs the amount downloaded (from the re-add time). Needless to say the amount uploaded will be a lot higher than what I have downloaded. I have one torrent 8.53GB that I am trying to download - not enough seeders. It is one of those in the above example. My ratio for this is now 55410.391 and still going.

So one needs to take these things with a grain of salt. If you can get the torrent, fine - can't, go on to the next one. If you are an initial seeder - seed as long as you are able (until you want to seed something else). Even if you upload the number of bytes that would indicate the size of the torrent - that does not mean any one person has the entire torrent - multiple transmissions of the same piece.