[cybmole]

OP here.

I have previously read much discussion of google drive issues.
I understand that it corrupts calibre operation when used as a live library.
inspecting my reduntant google drive backup, all the numerics in folder names look OK.
if I were to restore from that, then i'd do 2 steps. 1, copy all to a local folder. 2. then and only then tell calibre to use that local folder as an existing library.
if that did not work then , as has been pointed out, I could re-import every book to a new library.

maybe we need a definitive sticky on the issues with cloud storage; it would appear from recent posts that we don't have a consensus yet on exactly when/ how goolge drive corrupts things so maybe we also need more objective test results.

bear in mind that google drive is not an actual local copy of a cloud - it's not like a sugar sync or dropbox folder . its a "fake" folder whose contents exist only in the cloud. ( there is an offline mode but it is off by default )

let me start that ball rolling. I have side by side, my local calibre library & my google drive copy. I am opening each author folder in both locations & checking the 4 digit numbers. I checked the 1st 3 authors & get 3 out of 3 matches. so I conclude no corruption, which is what I expected.