qBT just killed around 600GB from 1TB content...

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qBT just killed around 600GB from 1TB content...

Post by NLS » Fri Nov 29, 2019 12:59 am

Well here is how it happened and I cannot really think of an excuse for such a destructive action...
Please follow the story, as this is the way to "replicate" what happened.

So, there is a collection I am interested that is around 2.5TB (for simplicity shake - it is some emulation stuff btw).
I already had around 1TB if this.
Someone posts a torrent, but I believe it is based on an older release of that collection.
So to test this theory, I get the torrent and hash check my existing collection.
*** DO we agree that hash check shouldn't be a destructive action? ***
Indeed the torrent is proven to be an older version of the collection, so many of my data check out ok, but many that I have, are reported missing (as they are older versions in the torrent), plus of course those I am really missing (to reach those 2.5TB).
* Note that I never "start" this torrent. Just added it and then asked to hash check.
When I see the state of this torrent, I don't remove it, but "deselect" (i.e. "Do not download"), all the contents.
It is possible that my data died right then. I am not sure.
I am not sure how qBT handles those ".unwanted" folders, but never shows any indication of actually doing any moves (and when it is finished).
That part of the story happened many days ago.
I left that torrent in my qBT client, but with unselected all files (so it showed as "complete").
Again I am not sure if I had "innocents die" already then.
So we come to today.
Another torrent pops up, that seems to be based on the current release.
So I get that torrent, again add it to qBT, NOT start it at all.
Start a hash check.
The hash check shows a REALLY low percentage of completeness. Something is wrong...
So I go into the folder structure and for the first time I notice that all (?) my files are in ".unwanted" folders, probably because I have that other torrent with all the folders deselected (set as "do not download").
So I go to that torrent and enable all.
* Note again that I don't actually start any of the two torrents (that "look" inside the same folder structure).
I go to file system and notice that my files are moved OUT of .unwanted folders and back to their original place.
Since I cannot look inside all the tens of folders, I do a quick search for ".unwanted" and then select all and ask Windows to give me the properties of the selection. It reports 83 .unwanted and 0 files. Great, this means that qBT moved all files off the .unwanted folders (because qBT itself never gives indication of that task finishing).
Then I delete the "old" torrent!
* Note, I am careful not to select to delete contents of course!
*** It is also possible that now files were killed! ***
I go to the "new" torrent now and ask it to hash check again...
...so it goes better than first attempt (where it showed a tiny percentage) but still shows most of the folder I know I have complete as empty!
I check the folder structure in Windows and I seem to miss a great deal of the folders!!!
I check properties, only to find out I have around 440GB from the 1TB expected!!!

...So somewhere in some of the steps above (which supposedly are all non destructive) qBT killed my files!
Was it days ago with the first hash check of the old torrent and then deselecting all contents?
Was it today, when I added the new torrent, then selected all in old folder, then deleted the old torrent (not contents) and possibly disrupted some move operation? (but then again, where are the files? Even a move in and out of .unwanted, is not deleting anything... it is a rename for the filesystem)
I am not sure what happened, I just know that (a) qBT managed to make 600GB of my data "disappear", (b) qBT never gave me an indication of start and finish of underlying move/rename operations. Possibly it didn't protect my torrent contents if it was in progress of such an operation when I deleted the torrent from the list.

I hope I don't trigger any defensive replies, I really hope we can pin point what went wrong and possibly add some "protection" (or alert or whatever) against such destructive action of the program OR user action.


I am thankful I had mirrored the files that vanished, plus recuva seems to recover them right now (but since it doesn't recover in place, I am currently spending around a day or so, recovering to other disk and then rebuilding the content)...

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