@Tourma
You're wise to want a #backup. I've never regretted having a backup. I've occasionally regretted the lack of one.

I have a dedicated partition just for disk images. Before dangerous operations, or just when I feel like it, I boot into a #Linux live image, use #cryptsetup to decrypt my root partition, and use #dd to back up critical partitions to my images partition. I use a script so that it's harder to make mistakes (by, for example, copying in the wrong direction). The script has several commands like this:

... plus some stuff for decrypting my root directory, which won't be relevant for your application.

If this is a one-off operation for you, and especially if you're only backing up a single partition, then you don't need to write a script for it.

Although I have an images partition, you could back up across the network. The essential thing is to boot into a Linux live image and make sure none of the partitions you want to back up is mounted.

The first time you look at a #Windows machine's hard disk under Linux, you'll find several hidden partitions. I honestly don't know what they all do, except that one, I know, is dedicated to telemetry. But you might be wise to back up the entire disk (in Linux terms, something like /dev/sda) rather than just a single partition (/dev/sda1). That way, you'll get all those partitions and the partition table as well.

I'd suggest seeking advice from someone who spends more time in the Windows world, just in case there's something I don't know about that end of things.

So today I tired #mkfs.btrfs and this works. I was using #gparted, which can’t create #encrypted file systems and so I created a blank (cleared) one, used #cryptsetup to create the #encryption on the device, and then created the brtrfs file system.

#GNU #FreeSoftware