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When I download a file in torrents, the actual download (seen in the Ubuntu 'System Monitor') is a bit more than the download observed in the 'Transmission BitTorrent Client'. Are torrents less efficient than regular downloads? Is this because my torrent client has to talk to a number of other torrent clients to get the file?

Is there a way make this difference smaller, keeping the download speed the same?

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Torrents work by trading a few extra bytes downloaded and some extra software complexity, CPU time, upload bandwidth, and additional active sessions in exchange for the potential to download the desired bytes at a much faster rate.

So it depends on how you define efficiency. If your primary concern is for transmission size, then torrents are not efficient. If your concern is how fast you get your data, they are great.

Each of the costs I listed in my first sentence are real. They are designed to not be a factor for most users, but any of them can be important in the wrong situation. For example, the small college where I'm network admin has a fixed limit on the number of simultaneous sessions we can push through our gateway at one time. BitTorrent users can generate in excess of a thousand sessions each. Just a few users like that and suddenly internet access suffers for everyone even though we have bandwidth to spare, because we can't process more sessions.

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  • If your concern is how fast you get your data, they are great - Not sure how. I am using a 512Kbps line and the download speed gets saturated with torrents. In this scenario, a regular download is much better than a torrent download. Also, will decreasing the default value of 'Maximum peers per torrent' from 60 to something lower make it fast? Oct 13, 2011 at 16:48
  • in general torrent gets faster with more sources, since it can grab more pieces of the file at the same time. Oct 13, 2011 at 17:31
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    @Praveen - Most of the time, the original source for a direct http download is only able to provide a limited transmission rate... say 100Kbps. Individual torrent peers are usually even more limited... say 15Kbps, but you'll put 20 or 30 of them (or even more) together to get a total speed of 450Kbps. If you're downloading a file from a source that can fill your 512Kbps link, then that source will be faster than a torrent. Oct 13, 2011 at 18:25
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Torrent speed depends on seeders, both quality and quantity. If a torrent only has a few seeders with slow connections it's not going to download quickly at all. Http downloads that rely on servers are usually more reliable. But a well seeded torrent can be astronomically fast, it's definitely where i've seen my download speed maxed out most often. Most hosts don't have servers that can match those speeds.

I'm not sure about setting your maximum peers, but I doubt it will help you. It's pretty common to set max upload and download peers to 300 when tweaking rtorrent, that would be for a seedbox with an incredibly fast connection and horrible specs. Transmission isn't quite as efficient as rtorrent without it's GUI but i'd consider it to be very efficient regardless.

I don't have access to Ubuntu's System Monitor but is it possible that the uploaded data is getting reported also? Unless you explicitly set it otherwise you've probably been uploading to other peers while you download, especially on more popular torrents. Even if you have set it otherwise you're also sending data to all the tracker URLs of the torrent, which would account for a little chunk of network usage.

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