Peer Download Percentages Increasing, but Seeder Is Invisible. How?

[Chris4877]

Hi, all!

I'm downloading a rather large torrent (51GB), which is behaving in a fashion that I've never seen before.

As you can see from the screenshots below, I've been downloading this torrent for quite some time, now, (over 4 days).

Now, I started downloading this torrent just before the Swedish police took down The Pirate Bay, but when I downloaded the magnet link, it was showing as having only 1 seed and about 10 or 15 peers.

When the torrent started downloading, the seed was visible for only a short time, (less than about 20 minutes), and it would reappear randomly from time to time. However, when it did appear, it would hardly ever download any data to my machine, and, if it did, the amount would be only very small, (less than 1MB).

This has been going on for over 4 days, now, but my download percentage is still gradually increasing, even though there is no visible seed for most of the time.

Not only is my download percentage slowly increasing, so is that of the other connected peers.

Also, on the summary page, the "Downloaded" and "Availability" graphs are showing steadily increasing percentage figures, (of course, it started at over 100% (when the seed was connected). Then the seed disconnected, (after only about 15 minutes). About 3 or 4 hours later, with the seed never having reappeared, the percentages were around 30%, and now they are around 64%, even though the total connection time of the seed has been less than 1 hour during the whole time I have been downloading this torrent.

I have attached 6 screenshots, taken over a period of about an hour or so, showing the progress of the torrent.

The shots are in pairs, one showing the peer detailed status page, and the other showing the summary page. I have drawn little black rectangles around the relevant details in each of these pages.

The "time elapsed" detail in each pair of screenshots will show a small discrepancy, owing to the fact that these screenshots were taken in real time.

It should be noted that the second pair of shots was taken about 20 minutes after the first, and the third pair was taken about 40 minutes after the second.

Also, I note that, on the rare occasions when the seed is actually visible, it always shows the same IP address and port.

My question is this:

How is it possible for all the peers downloading a torrent to increase their download percentages when the only seed is not only disconnected, but apparently invisible?

Thanks in advance for any suggestions.

Best regards to you all!

SCREENSHOTS:

First screenshot Pair:

Second Screenshot Pair:

Third Screenshot Pair:

Edited December 14, 2014 by Chris4877 (see edit history)

[The UnUsual Suspect]

It's possible the original seeder is using "superseed" option or "original seed", this presents them as a regular peer and they gradually report having new pieces. This method of seeding was designed to limit the amount of upload used by the original uploader so in theory they only had to upload each piece once and other peers in the swarm have to wait until it gets passed to one of their connected peers before they get it. There is really nothing "super" about this as it only slows down the process, but for an uploader that needs to limit his bandwidth it can serve a purpose but a lot of uploaders use it because the name "super seed" sounds better. BitComet added support for this a couple years ago but we changed the name to avoid confusion and prevent it's misuse. Other clients have also used different names for this.

It could also be a seeder that isn't always online and when they connect data is uploaded then passed among the peers until they are all at equal level. If this is the case you will see a seed appear from time to time, but if using superseed you won't know they are a seed as they appear to be an ordinary peer

A superseeded torrent will be slow but it will progress at a steady rate, an intermittent seeder will progress in spurts. Either way it could be a slow torrent until more peers reach 100% and there is a risk it may never complete.

[Chris4877]

Many thanks for your reply and the information.

Now I think I understand what's happening. :D

BTW, the "seed" has just re-appeared again. ^_^

The progress seems to be steady, rather than in spurts, so I think it will eventually complete. :)

Edited December 14, 2014 by Chris4877 (see edit history)

[Chris4877]

A superseeded torrent will be slow but it will progress at a steady rate, an intermittent seeder will progress in spurts. Either way it could be a slow torrent until more peers reach 100% and there is a risk it may never complete.

The progress seems to be steady, rather than in spurts, so I think it will eventually complete. :)

FYI, the torrent has eventually completed, after about 10 days! :D

This confirms my "the-glass-is-always-half-full" philosophy! :D