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Recently I have downloaded a game patch from a torrent. The total patch size was ~528 MB and the torrent has shown 235 MB as "wasted", with 0 hashfails. Some other things I remember about the download:

  • my client is uTorrent 2.2.1
  • While downloading, there were ~250 peers connected, the torrent had ~70 seeds.
  • My download speed was limited to 50 kB/s

When searching documentation to learn what "wasted" means, I have found a following mention in the uTorrent documentation:

In many cases, this is an indication that the swarm you are connected to is fake or poisoned and set up by some anti-P2P organization. ... Another source of hashfails may be your router.

I am not sure I understand this correctly, but it seems that the fact I have no hashfails at all does not match the situation described.

  • What can be a source of wasted data when there are no hashfails?
  • Is this something to worry about, and if it is, what can be done to improve it?
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up vote 5 down vote accepted

When you download from torrents your client requests blocks of data from multiple peers. Usually the first to reply gets used. If others also reply with the block that data is most often discarded, or wasted. It's nothing to worry about and is part of the normal operation of bittorrent.

share|improve this answer
I was surprised by relatively high amount of them (adding almost 50 % to the download), but if you say it is normal and nobody seems to have any other explanation, I accept it. – Suma Apr 1 '11 at 14:36
That seems to be a real waste of bandwidth. Don't P2P systems have something to limit these types of wastage? – K. Rmth Mar 11 '15 at 15:11

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