[millan]

I appreciate your clarifications very much Chaley
metadata is very important for me.
Question about moving the opf to where the book.
Could you please clarify if opf has any reference points to the book?
if so moving the opf my not work unless the new database created if then how?

Originally Posted by chaley

What I would do:

1. In one copy of the library, merge the OPF and the book files:
   1. Find a "duplicate book" where one folder has the OPF file and the other folder has the book & cover
   2. Move the OPF file to the folder with the book and cover.
   3. Repeat for all 3500 books.
2. Create a new calibre library named whatever you want.
3. In that new library, select Add books / Add books from directories ... (One book per directory)
4. Point it at the copy where you moved the OPF files
5. Let it run

If you are willing to lose the book metadata than you can skip the merge OPF & book step.