How to finally stop iBooks from unloading epub and pdf files

There is a problem with iBooks: books are getting removed locally and uploaded to the cloud, if the space is running low on the device. But with iOS 11 some users experience unwanted file upload even when there is no space shortage.

And there lots of topics and discussions all over the web, starting with official help site, Reddit, macrumors.

But actually there two ways to solve the issue:

  1. Remove iBooks
    Reinstall it from AppStore
    Download all the books.It might be useful also to do this afterwards:Settings > Apple ID > iCloud > iBooks: OFF
    Reboot iPad
    Settings > Apple ID > iCloud > iBooks: ON
    Launch iBooks
  2. Check the appropriate settings, stop iCloud syncing at:Settings > iBooks >Sync Collection: OFF
    Settings > Apple ID > iCloud > iBooks: OFF

    And then upload books to the device using wire, or just get them through Cloud Storage (Dropbox, Google Drive, Yandex.Disk or etc).

    As the downside, your notes won’t sync, but you will keep the books on your device.

  3. There is yet another hack to stop iCloud from deleting books: turning airplane mode.
    iBooks can't unload books, if there is no internet