I completely understand, but how will they access it? Over something like teamviewer where you can also see the screen and control the mouse keyboard would be preferable to ssh access where you have no idea whats happening until it’s over.

On the other hand, whatever he’s going to do he should hopefully know beforehand, otherwise it just sounds like a fishing session to try a few things.

$6 x 14Tb = $84 month x 12 months = $1008 per year, or did I miss read the prices?

How much are you backing up? Admittedly backblaze looks cheap but at $6 Tb leaves me with $84 pcm or just over $1000 per year.

I’m seriously considering a rpi3 with a couple of external disk in an outbuilding instead of cloud

When you install a dual boot system, Linux installs a grub loader. This asks you what you want to boot - windows or Linux.

Microsoft doesn’t place nicely with grub and I’ve found many occasions when a windows update mysteriously disabled it, and you can only then boot into windows.

If you only want to test the interface and see if you get in with it, you could create a Linux live usb. It’ll be the same but the os speed will take a hit booting from usb, so just be aware.

Been a while since I had the problem, but then been a while since I even wanted to boot windows anyway…

https://itsfoss.com/no-grub-windows-linux/