Sneaker netting the HDD is fine, but usb connections are relatively fragile and don't take kindly to being disconnected and reconnected too frequently, more especially mini-usb connectors.
So for a longer term solution you might want to investigate periodic synchronisation across your local network. Perhaps using something like Bitorrent Synch, which is free for personal use, it's available for Windows, OSX, and Linux on Intel and ARM, so it would be OK for your Raspberry Pi. If you were to run it daily, I anticipate it would run for a couple of minutes as it only copies changes (adds, removes and updates).
But you should still close calibre at both ends while it was syncing.
BR
Last edited by BetterRed; 01-01-2017 at 08:34 PM.
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