I have a Macbook Air (2015). It has two identical USB ports, one on the left and one the right.
I bought two identical USB flash drives and plugged both in. I'm copying a single large dataset onto both drives. The first transfer is complete, the second has just begun and will take another hour. I would like to disconnect the drive that I've already transferred the files to. I obviously do not want to disconnect the wrong drive, the drive with an active file transfer. But these drives do not have any kind of activity indicator (like an LED).
So, which drive is which? If the physical devices offer no clue, can I figure this out by consulting fstab or some other low-level system info? Do the physical ports have predictable locations on the internal bus, or anything like that?
I don't expect an answer within the next hour, but I'm still interested in the question academically. When the two USB devices are different, it's easy to know which is which because you put them there and are aware of their differences.
Also: this question is specific to 2015 Macbook Airs. If Apple did things predictably back in 2015, great for me, even if the *nix & Windows situation is the wild west.