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Solutions to 100% Disk Overload - Need assistance on last issue


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Greetings all - Warning, lots of info

Hopefully this will help some users out there. Several days of frustration on several of my utorrent servers have resulted in me sorting this out 90%. I have diagnosed several causes of why this happens and need help with just one which I have no idea how to fix.

All the servers are latest uTorrent 32 bit - Standard Windows Server firewall - No AV

I have on average between 30 - 100 torrents running on each server with sizes up to 150gb, so I hopefully have found many causes. Access speeds are 100mbs to 1Gbps

The cache settings vary, I shall discuss it more per cause, but for each cause I shall use 1024mb

In general, the cache setting does not effect much on the final outcome once your setup has you heading in this direction, as when the level cache level is breached, it shows the overload message and continues using memory. Once it hits 1950mb around about, it becomes unresponsive and pretty much "crashes" and does not write a crash dump as its still "active". I shall call this phenomenon "uTorrent Freeze"

Many of these causes only manifest on high torrent users, so probably only effects a smaller amount, but, having multiple of these settings can cause the amount you need to download or usage to become lower and lower. Lower usage users can probably have different setting for low speed low size torrents.

Cause 1 - Download speed is faster than write speed of the HDD.

If you can only write to your hdd at 60Mbps, then once you hit that amount of data flow, your cache starts filling up and your headin for a uTorrent Freeze

• Added note: If your hdd write speed is already near this limit and you start copying to the same location for long enough, this can cause the cache to be filled quickly and simulates a Cause 3 scenario

Solution: Test your hdd write speed, many tools out there. Then set your download speed to just under that amount.

Cause 2 - Disc Cache Setting: Reduce memory usage when the cache is not needed

If this is unticked, and you seed many, many, many torrents at high speeds, it can just fill up, and up till you get uTorrent Freeze

Solution: Must be ticked

Cause 3 - Disc Cache Setting: Write out untouched blocks every 2 minutes

If this is unticked, and you download a large amount of files (like 50-100gb) at the same time, all these untouched blocks start adding up in the cache memory, the larger the files, the faster this can happen, boom, uTorrent Freeze

Solution: Must be ticked

Unknown cause - uTorrent stops writing to disk (and possibly reading as-well) - I shall call this phenomenon "uTorrent Horder Mode"

How or why it goes into this mode is unknown to me, I have added some ideas below. I have a server where it is stuck in this mode. Other servers can enter this mode at random. But its not all the servers, so its probably isolatable once i remove more variables. utorrent takes, but does not give back. This server has 521Gb of space available, so it is not a space issue. It has 2 drives, main OS and storage.

Once in this mode, and diagnostics I have done:

•uTorrent continues to download into cache until you head for a uTorrent Freeze - This happens quickly

•Files complete to 99.9% and uTorrent is obviously waiting to write out the completed blocks - The pieces info tab shows all the finished parts just sitting there.

•Disable Windows caching of disk writes setting on or off does nothing to stop this mode.

•Preassign files on/off, no difference.

•Adding a new torrent works, and it start downloading, but, no new file is created on the storage drive.

•Also tested the above on the OS drive, same results as above, so its not a drive related issue.

•I can copy files from drive to drive, even to the exact location where uTorrent is supposed to download to and the files are copied with no problem, so this is isolated to utorrent only.

•Seeding also seems to be limited to what is available in the cache, now old file parts are accessed.

•Clean install - default setting with the above tweaked - same scenario.

So-far, the only common denominator is that all the servers having this issue, have been checking files (integrity check) after a crash etc etc. I can only but ponder if the issue is that whilst checking, utorrent somehow gets locked or frozen.

I hope the above info will help those users who may be affected by the uTorrent freeze, and that the devs can test and find the cause of the Horder Mode.

I shall update if i get any further info.


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  • 2 weeks later...

I've run into the same issue.

What I've noticed is that I had torrents downloading and a torrent with three big files (14-18 GB). I had downloaded one of the files. Then I wanted to download another one (18 GB) by switching its status from "skip" to "normal", which I did. After that my cache started to fill up and writings to the hdd stopped. I tried to reproduce the problem and managed to do so only with big files (>10 GB). I downloaded the folder with small files while the large file was skipped. Once I changed its status from "skip" to "normal", the cache bug appeared. When I started to download that file normally i.e. add torrent - ok, then everything went smooth.

I do not have pre-allocate and write zero.

I do not experience the cache bug while copying huge files or verifying huge torrents from previous crashes :), so I do not think it's my hdd problem.

I have Core 2 Quad and during the cache bug my processor goes up to 20-30% each core whereas normally it takes 1-2%. It stays so even when the cache is full and nothing is downloading.

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  • 2 years later...

It seems that uTorrent is still plagued with this issue 3 years later.


When I try to download a torrent which contains large files (for example a movie season with 2-3GB sized files), the memory consumption of uTorrent is sky-rocketing and consumes all my 4 gigs then the computer becomes totally useless..

I can't even kick out uTorrent from the task manager, disk usage is 100% also (both main and the attached disk). I have to switch off the computer.


I save my torrent data to an external USB disk, with a writing speed of about 20MB/s. I tried to limit the download speed to 5MB/s but it did not help, I observed this behavior of uTorrent several times, even with the latest beta (3.4.2 build 32537).

The other 2 settings mentiond by the OP are set as he advised by default.


Otherwise uTorrent works smoothly, but as soon as I open the torrent with large files, it brings my computer to its knees.

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  • 2 weeks later...


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