I’m looking to set up a test tracker torrent (bittorrent) at my place for family and the people who live in my block of flats.
Does anyone know what kind of bandwidth these consume with about 10 people connected at any one time?
If neither you nor the clients do anything to curb it, you can probably expect that the clients will simply grab all the bandwidth they can get.
If the tracker machine does not itself take part in the data exchange, the load on that machine will probably be pretty low, but I would not be at all surprised if 10 fast clients managed to saturate a 100Mb network between them. Especially if they all share a single Ethernet hub (as opposed to a switch), because in that case there will be lots of packet collisions so the network won’t be used very efficiently.
I’m looking at a wifi solution for this place (54Mb) so that should do fine.
I know that the data exchange will be a lot if I’m the only seeder but once others have obtained the file then it should cut down a lot I guess.
A little elaboration on my previous answer:
Do I understand correctly that this is a single, local network to which all of the clients are connected? In that case, setting up a bittorent server could be a fun experiment but it’s not going to be very useful.
The purpose of bittorent is to efficiently exchange data over a network, by using not only the data lines between the server’s upstream line and the client’s downstream line, but also the upstream bandwidth of the individual clients and the data lines between the clients. This allows you to spread out the required bandwidth efficiently over the network, as illustrated here.
However, in your situation there are no separate data lines between the clients; all of the machines on the network share the same bandwidth, so there’s not much to be gained from using bittorrent to share the load. You probably won’t notice a large advantage of using bittorrent, as compared to simply using a central shared fileserver to exchange files.
By the way, are you two different people, or did you forget to log out of a roommate’s Straight Dope session or something? 
BitTorrent also relys on concurrent downloaders. For a population of 10 that is not statistically likely.
My girlfriend actually
What I thought is that my family could profit from the fact that they would quickly find several seeders for the same file.
So while I only have a 25kb/sec upload, if several people in the building had the same files after a short period of time (I understand that we’re all on the same LAN) then the combined upload would be better for the folks in Ireland and cousins in the USA.
What I don’t know is even if I’m not seeding myself, what bandwidth the tracker needs to function correctly. If it’s just a case of the client connecting every 10 minutes to get an update on seeders and such then it’s fine but I thought that maybe there was more than that involved.
Well, I’m sure it’s a lot more than once every 10 minutes per client, but with only 10 clients maximum I doubt that the overhead of the client-tracker communication is going to be very significant. After all, other protocols have their own kinds of overhead, and bittorrent is designed to be pretty efficient.
However, I still don’t see what you are trying to do, sorry. You have a building with several computers in a LAN, all sharing a single Internet connection, is that correct? And you want to share files from a machine on that LAN with family in other parts of the world, over that single connection? And you believe that by putting up multiple seed clients inside the LAN, the combined upload speed over your Internet connection will be greater than if you had just a single seed client?
If you expect that several members of your family will often be downloading the same files from you at the same time, then putting up a bittorrent server would indeed be a good idea, because your family will then be exchanging data among each other and thus take some of the strain off your uplink.
But putting multiple seeders on your LAN is not going to help them getting the data faster than they otherwise would. How could it? If you have a 25kb/sec upload limit, then 25kb/sec is the maximum speed at which you can send out data. A single bittorrent seed will happily saturate that bandwidth all by itself; adding multiple seeds on your LAN will not improve matters and could very well hurt. Having multiple seeds is only useful when they are in different places, otherwise they just behave as a single client as far as the rest of the network is concerned.
Also, unless you have multiple Internet-visible IP addresses, the rest of the world will never see more than one of your seed machines.
Or am I completely misunderstanding you? Does your LAN have multiple different Internet uplinks, one for each client machine? In that case, using bittorrent would indeed be one way to improve your upload speed, but that would be a rather unusal setup.
I’m going to sleep now, hope things will be clearer when I wake up… 