On Mon 26 Jul 04, 3:45 PM, Rob Rogers <@.net> said: > On Mon, Jul 26, 2004 at 02:46:48PM -0700, Peter Jay Salzman wrote: > > On Mon 26 Jul 04, 2:37 PM, Samuel N. Merritt <[EMAIL PROTECTED]> said: > > > On Mon, Jul 26, 2004 at 02:08:22PM -0700, Peter Jay Salzman wrote: > > > > Question: > > > > > > > > How does the "distributed copies" get larger when there are no seeds? > > > > > > I think that "distributed copies" measures how many complete copies of > > > the file you could get if you took all the pieces that everyone has and > > > assembled them. > > > > > > For example, consider a five-part file. > > > Alice has: 1 2 3 4 > > > Bob has: 3 4 5 > > > Carol has: 1 2 4 > > > > > > You could make one complete copy of the file from all this, so there'd > > > be 1 distributed copy. If Carol got piece 5 from Bob, then you could > > > assemble two complete copies. > > > > > > That's the integer part of distributed copies; I'm not sure where the > > > fractional part comes from. Maybe it's the size of the largest > > > distributed incomplete subfile divided by size of file, but that's just > > > a shot in the dark. > > IIRC, that's exactly how it works. So in the above example you would > have 1.8 distributed copies. (Alice's 4 peices and Bob's #5 is one. > Carol's 1 and 2, and Bob's 3 and 4 make another, and we ignore the last > Carol's last peice because we alread counted Bob's) > > > ok. this was my understanding. > > > > > > Does the tracker ever inject packets into the torrent when needed (like > > > > when seeds == 0 and distributed copies < 1.0)? > > > > > > No. The tracker doesn't have a local copy of the file. If there are no > > > seeds and < 1 distributed copy, everyone's download will stall before > > > finishing > > > > this was also my understanding. but my question still stands: how does > > the distributed copies increase if there are no seeds? > > > > i'm looking at a bittorrent right now. it's remained constant at: > > > > seeds: 0 seen now, plus 0.983 distributed copies > > peers: 19 seen now, 98.4% done at 0.2 kB/s > > > > that ".983 distributed copies" has been creeping upwards. last i looked > > at it, about 15 minutes ago, it was at .97. i've noticed this happen > > before too. > > > > how exactly does that number increase when there are no seeds? > > > > pete > > In some newer BT clients there's an option for a mode called superseed. > If you activate superseed mode (usually only used by the original > seeder) you won't appear as a seed to the tracker, even though you have > a full copy of the torrent. It also activates a more intelligent seeding > mode. Clients will know which peices are available from other clients, > and will usually try to request the most rare peice the find to try to > increase the number of distributed copies faster. In superseed mode, a > seed will tell the tracker it has no peices. When a client connects to > the superseed, it will tell the client it has just received a peice (and > I believe tell the client that is the only peice it has) forcing the > client to only request that peice. Once that peice has been downloaded > by the client, the superseed will not offer another peice to that client > until it sees another client with that peice (meaning that the first > client had sent it on) nice. i actually wondered why i never heard of seeders giving preferences to rare packets. it seemed like an obvious thing to do.
thanks for explaining that -- not only does it make perfect sense, it also answers what (used to be) a mysterious question i've had for months. :-) thanks rob! pete -- In theory, theory and practise are the same. In practise, they aren't. GPG Instructions: http://www.dirac.org/linux/gpg GPG Fingerprint: B9F1 6CF3 47C4 7CD8 D33E 70A9 A3B9 1945 67EA 951D _______________________________________________ vox-tech mailing list [EMAIL PROTECTED] http://lists.lugod.org/mailman/listinfo/vox-tech
