How can everyone on a private tracker maintain seed ratios above 1? Is it mathematically impossible? (lemmy.ml)

submitted 4 days ago by lemuria@lemmy.ml to c/piracy@lemmy.dbzer0.com

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I know that private trackers require users to maintain a good seed ratio. How exactly does that work out mathematically? If a bunch of users have seed ratios above 1, does that mean that there are some users who will forever be below 1, and thus end up getting kicked out, thus resulting in the private tracker just... shrinking over time?

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[-] notabot@lemm.ee 10 points 4 days ago

A closed group of users can all have a seed ratio above 1.0, but it's a bit of a contrived set up. For simplicity, in the following examples we assume that each file is the same size, but this also works for other combinations.

Consider the smallest group, two users. If user A seeds a file and user B downloads it, whilst B seeds a different file, which A downloads, both users will have a ratio of 1.0 as they've up and down loaded the same amount.

For three users, A seeds a file, B and C then download a different half each, which they then share with each other. A has a total (upload, download) of (1,0), whilst B and C have (0.5,1). If you repeat this with B seeding and A and C downloading, then C seeding to A and B, you get each peer uploading 2 files worth of data, and downloading 2 files worth, for a ratio of 1.0 each.

You can keep adding peers and keep the ratios balanced, so it is possible for all the users on a private tracker to have a 1.0 ratio, but it's very unlikely to work out like that in real life, which is why you have other ways to boost your ratio.

[-] Saik0Shinigami@lemmy.saik0.com 10 points 4 days ago

I just want to point out one contradiction...

You mathed out how to maintain exactly a 1.0. But you asserted, "A closed group of users can all have a seed ratio above 1.0"

You didn't show how this is possible.

[-] notabot@lemm.ee 3 points 3 days ago

A valid point, trackers often give you a certain amount of upload credit for free, and there are often other ways to earn those credits too, so all users' ratios would be above 1.0, but that should have read "A closed group of users can all have a seed ratio of 1.0" if we're looking at just the data transfer itself.