1. Cool, thank you for you input on using larger drives. I figured it could but wanted to be sure before spending the money.
2. I know the PR4100 will rebuild itself if you remove a faulty drive and replace it with a new one, I am just not sure how it would work when upgrading the size and if there would be a better way to go about doing so than just letting the PR4100 do the work itself.

Thank you for your thorough response!

I figured there wouldn’t be an upper limit but I’ve been burned before in the past with trying to use too big of a drive in various applications over the past 3 decades of computer use so I wanted to be sure before dropping a lot of money on new high capacity drives for the NAS.

When I replaced the one drive a few months ago I just removed the faulty drive from the NAS and slotted in the new drive in its place and the NAS copied everything and was up in running again in a few days. It was only 4TB but it took awhile. I know it should be able to if I replace like for like sized drives but I wasn’t sure how it would be have if I start replacing 4TB drives with 20tb drives.

I do have a drive cloner already, buried in an old tech box in the garage that I could use but it is several years old (6 maybe?) so I am sure it isn’t as fast a a newer one. Maybe I will pick up one or two of the ones you suggested to speed the process along.