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Can I make a backup of my CC settings and CC's book database?
[Android] How do I reinstall CC without losing all my book information? has more detail on the steps.
You will need to copy the book files themselves. One way to do that is the one you suggest: use a cloud service as a file transfer agent. Another way is to use CC's sync updated books, which works because a missing book file is always considered "old". The steps:
- In CC go to Settings / Connecting to calibre and enable (check) the function Wireless device connection - sync newer.
- Connect to calibre as a wireless device using the line Wireless device / sync books.
- Wait.
If there is a network problem just run it again. It will pick up where it left off.