Transmission

I've been sharing a torrent for a little while, and with my poor upload speed the leechers are still a while away from finished. In my particular case, I have an upload ratio of 79%, however, none of the leachers has more than 51% completion.

In this case, I'm wondering; when Transmission shares blocks of a torrent, what control does it have over which blocks it sends, and what behaviour does it use exactly? In an ideal world, I would expect that my leachers (who have been relatively consistent) should be a lot closer to my 79% mark, as a result of sharing the least available blocks, so that as many as possible become part of the swarm, meaning that once I've shared that block to one user, the others can get it from users other than me, i.e - as the only seeder of the torrent right now, my focus should be on getting one copy of every block into the swarm as quickly as possible, and in an ideal world that would mean that once I hit a ratio of 100%, that a full copy of the torrent is out in the wild, floating around in its component pieces.

Obviously we don't have an ideal world, so there is some loss as a leacher I've given blocks A, B, and C to disappears, so I have to send them on to someone else, and similar cases.


I'm not complaining that this isn't the case, as I'm not entirely sure what Transmission's priorities actually are, which is why I'm asking.

It may actually be nice if the availability or progress grids (showing available/downloaded blocks) could change function once you're seeding, and show a kind of colour-coded "heat" map, showing at-a-glance how well a torrent is seeded by indicating which blocks are most commonly available.

Still interested to know some more technical details on this.

My particular seed, the swarm seems to be limited by whichever peer is at the highest completion rate, even though I'm well beyond a ratio of 1.5. It's like new peers are only ever receiving new blocks from me that the other peers are just as able to give them, surely it makes more sense for Transmission to focus on giving new peers blocks that others don't have, so they can start to contribute to the progress more quickly by getting more sharable chunks out?


Am just hoping for some confirmation as to what's going on, as it could just be that I'm being uncharacteristically unlucky in how well the data's being distributed, but it seems like the best thing for sharing a new torrent is getting at least 1 copy of every block out as quickly as possible, so as many leechers can start to contribute, before building up redundancy? It also seems weird given that Transmission appears to err towards sharing with peers that have lower progress, but if the blocks being shared are ones that other peers can give to them then it's time wasted. But the rate at which the furthest peers are progressing is fairly consistent with the rate at which I'm uploading to them.


Is there a good way to gather more information on sharing statistics? It's something I'm quite interested in

Ah, hmm, thanks for the response! I know Transmission is able to restrict which files it downloads, and attempt to prioritise the order in which it downloads them, does that mean that the decision as to what chunks are sent are entirely on the leecher's end? I would have thought that any non-prioritised requests could be decided by the seeder's client, unless such things don't exist in the bittorrent protocol?

I suppose I should read up properly on the protocols involved!

Another bump, but I'm noticing a pretty major drop-off in the speed that I'm uploading to the swarm; Transmission is uploading nearly evenly to all of my peers, all of which were on 85%, and have crawled up to 86%, where before I'd be seeing at least 10% a day. Bandwidth isn't starved as I've been uploading full-speed all day.

It just kind of seems like I'm now just struggling to ration out same block to each of my peers, which is wasting tons of time as I'm stuck crawling with 15% to go, when really I should have shared at least one copy by now. It's like all the best progress was made at the start, so it doesn't seem right that it's been falling off like it has; while I have been noticing changes in the peers, it's also new ones arriving, I've yet to see any leave, but the new peers seem to be getting the bulk of their data from the other peers (as my upload rate is horrible).