Upgrading storage on from a 2-bay JBOD

Hi,

I have a JBOD setup (I know, I know...) on a DS218+ (2-bay).

Have a few questions:

- I'd like to get new higher capacity drives and setup RAID/SHR instead. Since I have a 2-bay using JBOD, how do I go about transferring the data to the new drives? Do I have to do this externally?

- Is it worth a small upgrade on the DS-218+ (there's a sale on DS224+)? Mostly for personal data storage and some 4k Plex transcoding (which sometimes works OK, sometimes not, depending on audio/subtitles)

Thank you!