I would like to move HDD from mycloud into a new Mycloud EX2 ultra (diskless)

So, I have a My Cloud 3tb. For the sake of redundancy, I would like to move the drive to a mirrored (RAID 1) array. It seems I could purchase a MyCloud EX2 ultra (the diskless version), purchase an identical WD RED 3TB drive and drop both into the bays and plug it in and I would assume the 2nd drive would then build the mirrored array with all my old data still intact.

Will that work, or is there a step or setting or action I will need to take to make this work?

I don’t think the firmware for the My Cloud gen1 or gen2 is the same as the EX2 ultra firmware.

You would have to remove the hard drive from the single bay My Cloud in enclosure and install it into the EX2 enclosure then partition/format the drive using the EX2 interface. I don’t think you can simply install the hard drive from the single bay with all its data/files and expect it to work in the EX2 device. Different hardware and firmware are used on the EX2.