In order to sort my way through all the ebooks I have accumulated I have set up my Calibre with multiple libraries (Science, History Middle East, Horror, etc etc), which can be found on my hard drive as subfolders of the main Calibre library. I have had to create libraries with the same name and address within Calibre itself under 'switch/create library'.
Now I have a new computer. Transferring the folders off my current hard drive is no problem, but is there any way of accessing, backing up and transferring all those extra libraries I have set up within Calibre, or will I have to set them up all over again?