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utorrent - some questions regarding priority, end-game and hashfails


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Hi I am using latest stable utorrent 1.7.7 and is ok but I have noticed some things on torrents I have downloaded.

1 - it seems way too agressive in banning seeders/peers, on one torrent it kept banning the seeder so I changed ratio from 128 to 32 and was then ok, about 25% of hashes failed.

2 - seems to be a lot of hashfails, I am not using a dlink and am not using DMZ on my router, there is no 38. and 208. range ips.

3 - on a large torrent I am downloading (over 400 files), I have some files on high priority and some on skip. A few of the high priority files have been stuck on 97.7% complete for 2 days solid, so this leads on to the next few questions.

4 - I ordered the peers page in relevance order, most of my downloading is of peers with below 5% relevancy, all the seeders and most of the high relevant peers are not letting me download. They have d flag.

5 - Those letting me download every single one where I am not sending to them is below 1kB/sec, every single one where I am uploading to them as well the speed is much higher, does bittorent have some kind of algorithm that caps speeds to people who dont send to you?

6 - the only high relevant peer sending to me is probably because I am also sending to him.

7 - based on the last 3 points I am guessing if I set something silly like 50 upload slots because I will be sending to more peers they will send more to me.

8 - if there is no end-game made per file why not?

9 - do seeders prioritise low files first? the availability is lower for last files in torrent, yet if I unskip a early file the seeder sends, so to summarise seeder will send me early highly available file if I want it but not late low available file.

10 - often I connect to someone and then discconect very shortly after, particurly common with seeders, any ideas apart from maybe me auto banning them?

I am connectable, green tick on utorrent, port forwarded on router.

I have also read the entire faq and spent some hours searching this form before making this post.

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1 and 2 indicate potential major problems with either your hardware or the swarm as a whole. Leave the hashfailed peers banned. If the data actually exists on the swarm, it will make its way to you. Leaving the default ratio is actually better for you, as you will be dropping less data to hashfails.

The major stall you're experiencing while selectively downloading is one of the major reasons why widespread use of selective downloading kills swarms.

Your point #7 is accurate, setting such a high number of slots would be pretty brutal on your speeds.

#8> because at a data-transfer level, bittorrent as a protocol does not have any concept of files.

#9> That is one of many factors that seeds use to determine who they send to.

#10> Let those connections happen.

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Well I dont usually do selective downloading but half of a 128 gig torrent I already have, really the torrent should have been split into smaller ones but wasn't. So I dont fancy downloading 65 gig of data I dont need.

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I changed my upload slots from 4 to 15, and I am connecting to more of the better peers, even one seed let me connect for 5 minutes but then he booted me :(

What do you mean by resuming the files?

also any ideas as to why I dont even see most of the peers and seeds in the list?

I have max 250 peers per torrent set.

But see these numbers.

seeds 2(10) peers 126(440)

out of the 126 I am only connected to about 20.

I have also noticed the file I am seeding 100% done, every peer that connects gets below 1kB/sec. Cap is set to 30kB/sec. I am sending much higher speeds to people who also send to me so it goes back to my point their seems to be some internal algorithm that caps sends to people who not sending back. :(

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Average upload speed PER upload slot NEEDS to be at least 1 KiloBYTE/second at ABSOLUTE MINIMUM.

Ideally, it needs to be about 3-5 KiloBYTE/second while downloading...and maybe a little higher while uploading.

The reason for this is...the peers you're uploading to are MORE likely to reward you nicely with high download speeds from them IF you're uploading to them barely faster than anyone else.

Were you uploading really fast to just 1 or 2 peers, then there's only so much they would give back to you.

But if you're uploading at 3-5 KiloBYTE/second to maybe 10 peers, then each one is likely to give at least an equal amount back.

Below 0.5 KiloBYTES/second upload speed to a single peer...that peer's likely to just ignore you.

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Here is whats happened for me on this torrent.

120+ peers connected 2 seeds connected.

when 6 uploads slots set, I get 6 fast downloads and maybe 1 or 2 slow downloads (under 1kB/sec) so really very poor.

when I set 15 upload slots I get 15 fast downloads and again 1 or 2 slow downloads but also a seed sends to me. My total download speed is almost tripled when I changed 6 upload slots to 15.

Thanks for confirming that the bittorent protocol punishes low upload slot users, personally I think thats wrong but I guess its done to forcefully punish leechers (which I am not one of). If I am sending to someone at 5kB/sec or 15kB/sec it seems to make little difference.

Also one of the 2 97.7% files actually moved up now to 98.5%, I need to reboot my computer for maintenance but no chance now I got a connection of a seed :)

Everyone leeching of me on the 2nd torrent which I am seeding and I have a really crappy ratio is getting aweful speeds, and I cant help thinking utorrent is deliberatly sending low speeds because they not sending back to the swarm, Since that torrent is nearly all seeders it seems wrong to the downloader.

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You MUST lower your upload slots or you will CONSISTENTLY GET NO DOWNLOAD. The more you split your connection the SMALLER it appears to others. If available uTorrent WILL send as fast as possible to as many peers as possible.

Think of your upload as a water pipe. The more upload slots, the more sub-divisions you make in it. Multiply slots * torrents to get the number of subdivisions you allow your upload to TRICKLE out at. Lower is not a "punishment". It sends data out faster.

Alternatively, think about it this way: get a calculator out and figure out how long it takes to send 4194304 Bytes at different speeds. Since that is only ONE 4 MiB piece of a theoretical torrent, those timeframes are the MINIMUM times between requests to you as a peer. If someone is only getting 100 Bytes / second from you they are going to reciprocate less BACK to you when you request it.

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If you're trying to run lots of upload slots per torrent, uTorrent WILL correct that for you by not allowing all the upload slots to be active at once.

BUT...uTorrent will not prevent starting too many torrents at once and is forced to give each 1 an upload slot of its own. But only 1. :P

"Thanks for confirming that the bittorent protocol punishes low upload slot users, personally I think thats wrong but I guess its done to forcefully punish leechers"

It's not really done to punish "pure" leechers, it's done because dividing a fixed upload speed many different ways means next-to-nothing to lots of people at once. Each packet has fixed overheads...so if the packet is only 1 byte of data, that's like a 5 ton mail truck delivering a 10 gram postcard. Overheads would DOMINATE your traffic. On the other hand, if uploading quickly to fewer peers...then overhead is less than data traffic amounts, which is as it should be. :)

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guys did you read my posts properly?

I will explain again.

I started of with just 4 upload slots.

With the 4 upload slots I had abysmal downloading, the only people sending to me above 1kB/sec were the 4 guys I was sending to. Understand so far?

Then I upped to 6 slots and I noticed an extra 2 guys sent to me. Still with me?

Now I changed to 15 slots, now I get 15 people sending to me faster and now a seeder will send to me.

Fact seems to be, the utorrent/bittorent algorithm rewards people who open up more upload slots. I bet if I had just 1 upload slot even it went out at the full 30kB/sec I would only have that person sending back to me and and just a couple at 1kB/sec.

I do prefer to send to less people at faster speeds which is why I initially did 4 slots, but the sorry sad truth is I got punished for it. However I am going to raise the upload speed when I go to bed now so I will be sending faster anyway, also the speeds arent evenly spread, I am still sending at 5kb+ to a few people.

I am effectively only running 1 torrent, the one I am seeding has very little activity and is dominated by seeders so I am not doing much uploading plus everyone who downloads of me on that only gets 1kB/sec. I wonder if there is a bug somewhere because what you guys are telling me isnt happening to me in practice.

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30 KiloBYTES/second total upload speed...is roughly equal to the 320 kilobits/second total upload speed on my Speed Guide alternate settings chart.

And it allows 3 torrents with 3 upload slots each.

That's equal to 9 total upload slots for 1 torrent.

Or about 3.22 KiloBYTES/second average per upload slot.

So there's NO surprise here you at least see download speed improvements if you're just running 1 torrent and raising upload slots to at least 9.

Even at 15 total upload slots, you're still managing 2 KiloBYTES/second average per upload slot...and beating a lot of other peers in that regard.

Which is as you have seen and should come as no surprise.

The thorny problem is if you add MORE upload slots.

At some point, the gains become far less...even NEGATIVE because your average upload speed per upload slot has fallen below other peers -- AND below the cutoff point that many BitTorrent clients use for how fast you need to be uploading to them before they feel "obligated" to return the favor in a timely manner.

It also means you're not trying to get pieces out to other peers quickly, since NO peer completes a whole piece in a timely manner if the pieces are 4 MegaBYTES in size and you're uploading to them at ~1 KiloBYTES/second each. Worse, because upload slots may not be constantly uploading to the SAME peers all the time...the time needed for ANY peer to get a whole piece from you can skyrocket as you connect to additional peers. I mean HOURS. You become the "slow seeder" that almost everyone hates even if your upload speed is still pretty fast!

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I did some tests.

I kept upload at 45kB/sec and reduced upload slots back down to 4, my downloading slowed down and actually slower than my uploading.

I then raised to 60kB/sec uploading, there was no change in my download speeds.

I then reduced back to 45kB/sec and raised slots back up to 15 and my speeds went back up.

Finally I raised speed to 60kB/sec and kept 15 slots, this did raise my download speed a little but but not as much difference as the slots made.

I have now a 2nd torrent going but I of course do not want too many slots open so I am only allowing 3 upload slots on that torrent. I am keeping upload speed at 45kB/sec now when I am on the pc, and 60kB/sec when I am not on the pc.

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I am just seeding now and I see the speeds are much more balanced, so I see now, utorrent will always give downloading torrents higher priority than seeding torrents, now I am only seeding the torrents have equal share of my upload bandwidth. I also have lowered the slots now I am only seeding but have kept the same upload speed cap.

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