Suddenly too much downstream traffic when seeding

[kb-pos]

I got a nasty surprise last month.

I have a nice 100/100 connection but the level of service I pay for allows me 80Gb/mo in incoming data from outside the country. This covers ALL traffic, HTML, torrents, etc.

Normally this is no problem and I seldom approach my monthly quota.  This past month, however, I went WAY over.  My ISP sends out an automatic advisory when I reach 80% of my data package.  Last month there was a glitch in their server which caused it to fail to properly report data use (they also have a page where I can see my data usage in 6 hour increments).  For that reason, they gave my 30Gb over use at no charge.  But I still ended up going over that, too.  In fact, I did a search on the computer for files with creation dates within last month.  I added them all up and it came to less than 25Gb.  My total data use for the month was >130Gb.

After performing a few experiments I determined fairly conclusively that the problem was uTorrent.  Even after a torrent was complete there was still incoming traffice.  I *am* aware that there will be *some* downstream traffic when seeding, but I was getting something like 690Mb of downstream traffic in a six-hour stretch overnight with *only* seeding going on and no web browser open.  If I shut down uTorront my downstream traffic dropped to zero.

Part of the puzzle is that I recently, i.e. last month, installed uTorrent on my newest hardware.  I had simply never gotten around to moving my torrent activity to that machine until now.  Previously, my torrents were all running on an XP machine powered by a Pentium D @3GHz and 4Gb RAM.  The newer computer is Win7 with an i5-2405S @2.50GHz and 32Gb RAM.

Some of the settings in 'Prefences' in the newer machine were actually more conservative than in the XP setup.  As in the XP machine I had the minimum ratio set to 200% and the minimum seeding time to 4320sec (3 days).  With that setup I was frequently gettning very high share ratios.  I had similar settings on the faster Win7 machine but with some lower settings for number of connections, etc.  In an effort to further diagnose the problem I tried a radical change in my queueing.  I set the minimum ratio to 500% (5:1) but reduced the minimum seeding time to 60min (1 hour) to see what, if any, effect that would have on my data use.  The effect was immediate and positive.  My downstream data use, after torrents had completed, fell to quite tolerable levels.  Overnight data use is now generally well below 50Mb for midnight to 6AM.

As I mentioned above, I know that there is *some* downstream traffic even when only seeding but why the sudden huge increase?  Is it the faster hardware?  That is the only thing I can think of that is new/different.  Could it be the latest update of uTorrent?  I think I updated at about the same time I installed it on the Win7 machine.  I've got uTorrent still running on the XP box but the torrents are rather old and have almost no activity.

I mentioned drastically reducing my seeding time.  I don't want to be a hit-and-run type but I also can't be everbody's mule, either.  I'm happy to share per normal torrent etiquette but this past month is something I can't repeat as it ends up costing me extra.

So, finally to the questions at hand:

1) What would cause this sudden increase in downstream data?

2) What can I do to allow longer seeding times while at the same time curbing the unwanted downstream traffic?