At a high level, if I catch your main point correctly, you have discovered a way to use an external drive with the HAPZ1 while preserving the ability to share the drive with another computer. Is that correct?Yes. The drive could be disconnected from the Sony, then connected to a computer which has the Paragon ExtFS program installed, and files could then be copied from it to the computer or vice versa.
Can you preserve existing data on an external drive while formatting it for use with the Sony?No. Formatting a drive destroys all data on it. However, after the Sony formats the drive it could be reconnected to a computer, and the same files copied to it if they are backed up on the computer (or on a different external drive that is connected to the computer), and if the ExtFS program is installed on the computer.
I know what an external USB drive is, but you lost me on the rest. No doubt, most of the readers will understand what you mean, but for me, unmounting the Ext partitions from windows sounds like an exercise in voyeurism or exhibitionism, or possibly both.:-)
When the Sony formats the drive, it would presumably format the entire drive into a single Linux-compatible Ext partition, not into multiple partitions as I did experimentally. Therefore you would not have to perform the process I described of ejecting the drive via the Windows "safely remove hardware" icon. And the unmounting process I referred to occurs automatically when the ExtFS program is closed.
So all you would have to be concerned with if you wanted to disconnect the drive from the computer while the computer is operating, assuming you are using Windows 7, is to locate the icon for the ExtFS program in the lower right corner of the screen (it looks like a large letter "P"; also you might have to first click the upward facing pyramid-shaped symbol in that area to see it), then right-click the icon, and then left-click the word "exit" which will appear.
As with many computer-related things, what seems daunting at first becomes trivial once you see how to do it.
Best regards,
-- Al