Multiple torrent connections simultaneously go to 0 KB/sec. Why?

March 14, 2013 6:52 PM

I've started DLing torrents from a tracker I was recently introduced to, after only having have some experience with one other tracker that's now gone, and I'm encountering a minor issue that puzzles me. I've noticed that periodically, all my torrents will simultaneously go from whatever speed they've been DLing at to 0 KB/sec, and then all return to their former speed at the same moment as well, after a delay of up to several minutes. What could be the reason for this?

I never encountered this issue when I torrenting occasionally before, and nothing about my system, connection, or application settings have changed since then. (I am, btw, on OS X, using Transmission, and have an ADSL 6 Mbit connection.) This happens on an irregular basis, and the number of connections, as well as their individual or combined speed do not seem to matter. Two files DLing from one seeder each at 10k/sec will behave this way, in the same way that one file DLing from five seeders for a total of 300k/sec together with another DLing from one seeder at 20k/sec will. (I haven't had more than a two or three files DLing at the same time.) There have been no files uploading (generally old and not too popular files...).

The seeders I am DLing from are always spread around the earth in different locations, so it cannot be that this is due to their internet connections, so an obvious conclusion is to assume that it has something to do with mine. I phoned my ISP, but they do not officially support torrents, and could not offer any explanation for why this might be happening (they have also publicly denied traffic-shaping).

This is not a huge deal -- the few torrents I DL do complete in a reasonable amount of time -- but I would like to know what's causing it if possible, and if it does have something to do with my own ISP.

Thanks for your insights and answers!

posted by anonymous to Computers & Internet (7 answers total)

Check to see if the rest of internet is working for you while the torrents are down to 0 kbps. If yes, then (just as for me) it is your ISP. If no, I am sure someone else will come along soon to sort it out.
posted by vidur at 7:20 PM on March 14, 2013

This can happen if the tracker gets real busy for some reason. One tracker I use does this about dinner time every night. I asked one of the mods, and he says that's when they run backups.

You can ameliorate this to some extent with "DHT", which is a way of finding other torrenters without any tracker. You should make sure that DHT is enabled in your torrent program -- and if it doesn't support DHT, you should switch to one that does. (Like uTorrent.)
posted by Chocolate Pickle at 7:21 PM on March 14, 2013

Dealt with this one multiple times at multiple different places. You're creating too many outgoing connections for either your router, or modem to handle(or if you have one of those modem-wireless router combo units, eugh, even worse)

You need to go in to the settings in transmission, then to "peers", then set the maximum number to something less than 200. try 150, then 125, etc until this quits happening.

On particularly crappy networks, i've had to set this really low before. But when you get it right, it'll instantly solve the problem.

The issue isn't even the number of active connections transferring pieces of your files, but the attempted connections reaching out to other peers to try and start downloading pieces.

You can solve this problem by getting a nice router and putting your modem in bridge mode(google it + your modem model number), or just a nice router/modem combo. Netgear for instance makes some great ADSL combo units that are amazing for lots of inbound/outbound connections and requests stacked up.
posted by emptythought at 9:37 PM on March 14, 2013

Other ideas:

If they are large files, you may be overloading your disk.

As mentioned above, you may simply be overloading your connection. Try to get a really good idea of your upload speed (Speed Test), and set Transmission to about 80% of that speed. Upload traffic at the highest end of your "spectrum" will generally bork your entire connection.
posted by kuanes at 5:39 AM on March 15, 2013

I second disk overload. Most programs aren't very good at showing that, sometimes just a minor text note at the bottom of the screen you really have to pay attention to notice.
posted by hobo gitano de queretaro at 6:03 AM on March 15, 2013

If your ISP throttles like mine (Clear WiMax), then try forcing encryption.
posted by oceanjesse at 8:39 AM on March 15, 2013

My guess would be that it's your router getting bogged down.

Disk reads/writes simply from downloading wouldn't be an issue unless you have an absurdly fast connection. The problem might be disk reads/writes if the program is busy doing a CRC on completed downloads, though. These can take quite a while, and if a few happen at the same time, it could eat up all the disk I/O and leave the program with a full write buffer and nowhere to put it.
posted by matlock expressway at 3:26 PM on March 15, 2013