Utorrent Disk Overloaded

[Bartolome Beacham]

Im using uTorrent 3.1.3 and I'm getting the error "Disk Overloaded 100%" after the download speed reaches 4-5 mb/s. It lasts about 1 minute, it starts again with full speed and then it displays disk overloaded again. After the second "disk overloaded" error, the download speed raises to maximum and stays that way until the end of the torrent.

This is a very old problem I've had with utorrent since version 1.6.1 and have not found a solution all these years. I tried to tweak the caching settings (as suggested on other forums) but with no luck.

Now changing this setting to a high number depends on two main things. The speed of your internet and the speed of your hard drive. For this guide we assume that whatever the maximum speed of your internet line is, will be the speed you will be downloading at.

So if for example you have a 50Mb or 100Mb internet line which are becoming common in the western world and most seedboxes and cheap rented servers start at 100Mb you will probably want to set this value to a high number. Perhaps 512 or 1024 (512MB & 1GB respectively).

I've created the following image to show you how having this large cache makes an impact on your downloads. Remember, if the cache becomes full and your hard drive cannot keep up with the pace of incoming file pieces your downloads will slow to a crawl or stop entirely.

Now as seen in the above image having a small 32MB cache is easily filled within a few minutes. The Hard Drive here is writing out the information as fast as possible but it cannot keep up because the randomness of the incoming files is simply to high. But when we increase the cache to 1GB we are able to sustain full speed downloads for an hour or more. Again this assumes you have a pretty average & modern 1TB or larger hard drive.

...below the Override cache size setting, there is a 'Reduce memory usage when the cache is not needed' check box. You'd want to uncheck this because a full cache when seeding hundreds or thousands of torrents is very important. It reduces the chances that your Hard Drive needs to retrieve a piece from a file to seed to another user. Now don't worry, if you begin a download anything that is stored in the cache for seeding will be removed as your incoming downloads demand more of the cache space. Downloading always takes precedent over Seeding when it comes to Cache use.

Under the 'Enable caching of disk writes', there are two check boxes. [Untick 'Write out untouched blocks every 2 minutes' and tick the 'Write out finished pieces immediately' box.] Those tick boxes are very important because you don't want your disk sitting idle for the first two minutes of a download when it could be clearing out the cache for more data. Those two minutes can really help. Writing out finished pieces as soon as possible is the most desired option.

Under 'Enable caching of disk reads', you'd want to untick the box that says 'Turn off read caching if the upload speed is slow'... [This could save] your hard disk a whole bunch of extra read operations and seeded more users before others.

The option directly underneath that one is 'Remove old blocks from the cache'. Similar to the above option you want to untick this because you want the Cache to always be full. A full cache is a well utilised cache and you never know if another user is going to request the same piece of a file that you just served to someone else, save the disk some extra work.

The last option here is 'Increase automatic cache size when cache thrashing'. You can enable or disable this option it doesn't make any difference once you've overridden the automatic cache size at the top of this menu.

Now although that was the last option in uTorrent 3.2.2 some of you may be using older versions of uTorrent which also include the option to disable Windows Read and Write Caching. I would suggest you to tick those and disable the Windows Caching because you've already set a very large and well utilised cache in uTorrent and it is unnecessary and problematic to also utilise the Windows Caching. In the event that your PC were to crash for example Windows may still be holding over 1 GB of file pieces that uTorrent considered already written to disk and when you open your client again you'll find that some downloads didn't get completely saved to disk and will need to be checked for missing pieces.

Disk I/O system completely rewritten. Now multi-threaded and high performance. It will take advantage of multiple disks, perform better with even just one, and no one disk job can block everything (e.g slow network blocking local I/O, or allocating files)

You're getting disk overload errors because torrents upload and download pieces non-sequentially. Unlike a local file transfer, your drive is having to read and write hundreds of random parts of the file(s) all the time.

I fixed it by bumping up cache to 1GB. It seems to have this problem only on large torrents with many files, over 30, in my case. Problem is that disk needs to write blocks to many different locations and it gets too busy. If cache is big enough it will optimize writes to make it more sequential....

Sol: Manually override the value and set it to 1000MB, this is the max safe value I have been using for years. Also uncheck the box for "Reduce memory use when not needed", otherwise the value we set would not be meaningful.

Then I realized that in 2.2.1, the option to disable Windows Disk Write Cache was still present, though I checked the boxes, I MUST USE ADMIN PRIVILEGE to open utorrent for them to work. Guess what? It finally works for me.

Recommending downgrading is NOT supported and hasn't been for 8 years. Running the current version of uTorrent as administrator will have the same effect as turning off the windows cache because uTorrent now attempts to do so without a way to not do it.

For the increase of cache size, the reason it helps is the downloading speed can be very high (50MB/s) in my case, 32MB cache is too low to be an effective buffer. 1GB can be too high, but it's just a worry free value to handle the high download burst.

Sadly making the client run as admin does not help. My system RAM usage still keeps creeping up even if the actual utorrent.exe proces does not use more RAM or the current cache keeps stable at a certain amount.

For less than 30 min of Downloading, the RAM that was released after the Download job was done was 1 290 MB! That is very bad as it slows down my PC when it starts reaching my RAM limit and starts paging.

The last build that still has the options to disable the windows disk caching is 3.1.3 build 27498 which i was using untill now and seems i will have to continue using since getting 1.2GB RAM used for a 30 min DL job is just unusable for me.

Those settings seem to help, but it is not perfect.I still get about 200-300MB RAM overhead fairly quick at which point it starts to stabilize(or at least increase very slowly) and then after a few min or so it drops back and the cycle starts again.So it is much better than the 1GB+ i used to get, but not as good as the older version that i used where the only RAM usage i got was write cache + read cache + client initial usage.

The only downside is that now the size of the torrent is not immediately taken into account when Windows calcualtes free disk space.It was nice that when adding multiple torrents i could instantly see how much space is going to be used by the new torrents and how much sapce i have left, but i keep more than enough free space so not a big problem.

There is one problem tho with the latest stable version.The UI hangs to Not Responding fairly easy.While downloading if i click between any of my other(stopped) torrents after a few clicks it freezes and hangs.Once i even had to kill the client from the Task Manager.

PS:It seems that the situation with RAM usage did not improve for the uploading jobs.Unlike the DL jobs where after a certain time the RAM gets released with UL jobs the RAM just keeps going up.I even tried the beta which didnt help either.Sadly the new versions are still not usable for me.

Has anyone found a solution? It's so annoying that I'm considering finding an alternative to uTorrent. It happens all the time when a torrent with several files is added. uTorrent becomes unresponsive, and overloads the disk for a while.

Solution; the disk partition which uTorrent is downloading files to needs to be formatted as NTFS. A FAT32 partition may be converted to NTFS without loss of data. An exFAT partition needs to be formatted. Also, make sure that "Pre-allocate all files" is disabled, and that "diskio.sparse_files" in advanced settings is set to true.

File size seems to be an issue as well. I just added a 30 GB file, and observed both uTorrent and the computer performance in task manager. It started downloading at high speed, and suddently it just dropped to zero. Task manager showed that the HDD was being overloaded, while something was constantly writing at around 100 MB/s. It stayed this way for a couple of minutes or so, before it dropped too, and the torrent started downloading at high speed again. From there on, the HDD was writing around 12 MB/s - the same speed as uTorrent was downloading the file. So my question is, what is uTorrent writing to the disk when a download is initiated? I repeat, the HDD was being overloaded at around 100 MB/s for a couple of minutes or so - while there was nothing being downloaded through uTorrent...

There's no issue when downloading large torrents to the SSD. However, all hell breaks loose when uTorrent is moving the completed download to the HDD. I also changed uTorrent's priority level to low in task manager/details, but it seemed to be ignored.

As far as I can see, the issue is caused by allocation. It seems as it's pre-allocating files despite that the option is disabled. Why does it have to do this? The issue may probably be avoided by checking/monitoring available disk space before the download begins, and then allocating disk space in realtime.

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