Best way to move data from Linux to Unraid inside the same case?

Hello! I’m about to change my Linux server into an Unraid one and I need some advice.

I had just 1 4TB HDD on this system with Linux Mint (and a 256GB SSD for Linux itself).
Now I got 2 more 4TB HDDs and I plan on creating an array with 1 parity drive and 2 storage drives. Nothing fancy.

The thing is that I have about 1TB of data on the original 4TB HDD that I’d like to keep and move onto the new Unraid array. So the idea is to:

  1. start with the 2 new drives as 1 parity and 1 storage
  2. move the data from the original HDD to the array
  3. wipe and add the original HDD to the array as a second storage disk

This is all done with the same hardware, I am just booting from the Unraid USB drive instead of the Linux SSD. So the original HDD is already there, connected and available to be read.

Is it possible for Unraid to copy from the original HDD to the array formed by the other 2 disks, before wiping it and adding it to the array as well?

Alternatively I guess I could connect it to a different machine and copy via the local network, as per usual with Unraid. But I was wondering if I could avoid removing and placing back the original HDD.

Sure, you can absolutely move the data internally. After you install Unraid, install the Community Apps plugin, and then from the Community Apps install Unassigned Devices, Unassigned Devices Plus and Krusader. Unassigned devices lets you mount devices outside of the array, like your other hard drive. Krusader lets you move files between drives with a GUI.

If you’re familiar with the terminal, you could also use Midnight Commander, which is built-in, instead of adding Krusader. If you want to try that, just open a terminal and run mc