@Divingduck I see, maybe the sheer size of it makes it a problem somehow, I don't know
@BetterRed, thanks
long story short, I managed to import the library
longer version:
- the archive was on the disk sitting in the icy box docking station, so it wasn't automatically checked for errors by fsck – I run fsck and it reported and corrected several minor inconsistencies (inode extent tree could be shorter)
- a couple of failed import attempts (both gui (just freeze) and calibre-debug ("Killed" message))
- moved the archive to the system disk
- more failed imports (gui and calibre-debug)
- finally, the success
I'm out of the woods now but I still don't know why the import failed so many times and then, magically, succeeded – so I'd like to learn that other decompress method, it might come in useful one day also a more permanent solution would be nice