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.
Ah ha! Thank you, this was one of my worries with increasing the capacity, I was worried that even after replacing the 4TB drives with larger capacity drives that the new drives would still only be limited to the lower capacity partitions. I wasn’t sure if there was a way to increase them.
My work around for this was to back up all the data on the NAS currently (only ~7.2TB) onto an external drive. Put the new larger capacity drives into the NAS, format them properly and setup the RAID as needed and then transfer the data back onto the new fresh larger capacity drives in the NAS from the external drive.