First: Move those (soon to be archived?) books to a
different drive than your (new?) Calibre Library is on. Calibre makes a COPY for its regular use. That is 320G

of books that can exist at one time
Second: do no more that 50-100 books at a time.
a) Things get a chance to be posted to the DB (in case of a hang/crash)
b) you get to see the progress
c) You can 'spool off' the completed
source books to free up space