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uTorrent write cache bug

a guest Apr 8th, 2012 1,647 Never
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  1. http://forum.pleasuredome.org.uk/index.php?showtopic=17928
  2.  
  3. After an extensive test, we uncovered a flaw in uTorrent's caching system for writes, which can be reproduced.
  4. To be precise, the "Disable Windows caching of disk writes" option, which is enabled by default.
  5. Enabling this option bypasses the Windows caching system for writes.
  6.  
  7. Discussions in the forum about file corruption made us decide to do some tests.
  8.  
  9. What we did is download the files from the "Mame 0.138 Titles" torrent.
  10. The torrent contains 6469 small files (not zipped).
  11. First we used uTorrent v2.0.2 with default settings.
  12. Saved the files in e.g. "d:\mame\titles" (short directory names are required for clrmamepro) and stopped the torrent when it finished.
  13. When you scan (check only) with clrmamepro and the provided datfile, it will result in reported errors (wrong size and unneeded files).
  14. With each test cmp reported errors with different files.
  15. We removed all the files and then downloaded the same torrent with v.1.6.1 up to v1.7.7 with fresh settings.
  16. Scanning the set with clrmamepro produced no errors (except the unneeded _ReadMe_.txt file)
  17. It went wrong when testing with v1.8 build 11813, which started producing errors again.
  18. One of the changes mentioned in the changelog of that version:
  19. QUOTE
  20. Other major features are bypassing the Windows system cache (see the Disk Cache settings)
  21.  
  22. The same test with v2.0.2 and "Disable Windows caching of disk writes" disabled produced no errors (except the unneeded _Readme_.txt again).
  23.  
  24. The uTorrent write cache problem can be bypassed by going to:
  25. Options -> Preferences -> Advanced -> Disk Cache
  26. and disable (uncheck): "Disable Windows caching of disk writes"
  27. However, with version 3.1 and later even this bypass won't help anymore!
  28.  
  29. We will (try to) report this to uTorrent development (Status: uTorrent devs answered in this thread...).
  30. To keep this thread readable, post clear and relevant questions/answers only please!
  31. The more useful information we get, the better we can help to get this solved.
  32.  
  33. NU, Petr1fied and ARMAX.
  34.  
  35. This post has been edited by newuzer: Mar 10 2012, 08:46 PM
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