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BitTorrent couses me extreme fragmentation; throttled download speads


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I have Win 7 x64 and the latest BT version. I use the 'sparse files' option for allocation but I tried the other options too for troubleshooting.

When I checked the pre-allcate everything option, my downloads stopped soon and the client wrote the disk is full (even though it actually had much more free space than the size of my torrent jobs), and I couldn't even fix this without resetting my PC. Then I tried it's default allocation: I don't know what went wrong with that but it re-checked every download jobs and when checking a very large one (>90 GiB) I suddenly got a BSOD. After resetting it started the checkings again I didn't want to get blue screan again so I swithced back to 'sparse files' it at least didn't crash my OS.

Please note that I have plenty of free space on the drive BT uses and the free space is in one chunk, yet fragmentation still occures. Also I don't remember this happening on Win XP.

The client sometimes still decides after start to re-check the download jobs seemingly at random. It's quite annoying especially when you have a >90 GiB job.

My other problem is with the download speeds. I have a pretty fast connection (25/5 Mbps), but BT doesn't let me exploit my full download speed. The highest speed it allows is about 1.4 MiB/s but most times I'm well under even that. (Before you ask: of course I'm talking about well seeded torrents wich could allow much higher download speeds. And I don't have incompatible softwares.)

I tried many things to fix this: set a global max upload speed low enough to allow overhead traffic (500 KiB/s - my usual real max upload speed is around 700 KiB/s), switched 'bt.tcp_rate_control' off (it also throttled the download speeds seriously), set the maximal numbet of connections to 2000 and per torrent to 500 and tried messing with 'bt.transp_disposition' values but it proved to be best on default 31. I also tried useing a traffic shapeing software (CfosSpeed), but when the client throttles the download speeds traffic shapeing has not much use. So now I'm totally clueless now about this.

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and the client wrote the disk is full (even though it actually had much more free space than the size of my torrent jobs)

Disk Overload isn't the same as disk full.

I actually just went over this on the uTorrent forums.

Preallocation of files causes MASSIVE INTENSIVE disk usage unless you're using sparse allocation. Admittedly it causes fragmentation, but there's not much that can be done about that.

set the maximal numbet of connections to 2000 and per torrent to 500

Have you tried lower numbers than that? Having those higher might actually slow you down rather than speed you up.

Additionally, the uTorrent troubleshooting guide (from http://forum.utorrent.com/viewtopic.php?id=15992) might help some of your speed issues.

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Thank you for your help and for the quick answer.

In the uTorrent documentation I read that sparse files couses fragmentation only if the disk is nearly full ad I'm downloading something larger than the remaining free space, that's why I was so puzzled that it couse fragmentation even on a fresh-formatted and large drive.

By the way, when I tried the pre-allocation the messege I got stated that the disk is full not "Disk overload". But it might be just a translation error becouse I use a localized version.

About the download speed: your tips were helpful but I still can't reach higher speeds. Now I think that my ISP throttles the downlod speed. I didn't think about that before becouse I never heard about that: I always heard they may restrict the seeding (wich they fortunately don't do) but never hard that they may do the same with downloading too.

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