Transfer disk from EX4100 to PRO4100

I have an EX4100 (4 bay) with 2 disks installed. I want to upgrade to a PRO4100 for the better CPU. Is it possible to power down the EX4100 and physically migrate/transfer the disks to a diskless PRO4100 and retain the data?

If not, what’s the best way to migrate? Do I have to buy a PRO4100 with 2 blank disks and do a data copy?

You can follow the steps provided in below article to migrate your disks in My Cloud PR4100 enclosure.

How to perform a Manual RAID Rebuild on a Western Digital My Cloud Network Attached Storage Device

Thanks. So when I take the disks out of the EX4100 and put it into the PRO4100, will it auto-detect that a rebuild needs to happen?

Yes, you will get a popup in the dashboard notifications. Also, I would suggest taking a backup of important data files at two different locations to prevent data loss issues.