Joe thanks, don't have stomach to change anything on these drives. They have ton of space. That said, they all say APFS on them now.. so maybe Mac OS did this anyway.. They all have the confusing Container, and Data thing going (which I still don't) understand.
If when these drives get replaced I learn all that for sure.
I would guess I could use them another 10 years? The are about 4-5 years old now.
I found this
grocery analogy helpful (here is the relevant part):
"A brief refresher: APFS is Apple’s modern, SSD-optimized replacement for the once-modern filesystem that’s been in use for many years. APFS is much more sophisticated than HFS+, allowing more flexibility for how data is structured and kept secure and separate, as well as offering particular features suited to SSD. The units of measure on an APFS formatted drive are containers, which are collections of volumes. In HFS+, drives were partitioned solely into volumes. One way to think about it: HFS+ was a carton of eggs, each egg a volume. APFS is a box that contains cartons of eggs.
Each APFS container has a fixed portion of the drive’s storage space allocated to it (as in partitioning) or can fill the entire drive. But volumes within a container share the container’s allocation dynamically. In most cases, adding volumes to an existing container makes more sense than adding containers, because volumes can grow or shrink without any work on your part. This allows the greatest flexibility."
