Data loss situations

[earthq]

I have seen several posts about data loss and I am concerned about under what situations, actions or bad practices this woud or does occur.
I.e. something I found:

- A book referenced in DB, folder and book exist, but the reference shows no format available. If you hit try to add the existing book you will end up with a cero byte file.
To fix the situation make a copy (with a name diferent that the expected is ok, or rename the existing), so when adding it it will create the copy and reference it properly on db. Then delete the "renamed" copy.

Other situations might include copying, moving or renaming files directly on file system, dragging books in library folders to calibre, etc.

Regards.