I have a Western Digital USB-powered spinning hard disk, perhaps called a Pocket Drive or some similar market-speak. I have a Samsung T-5 SSD. And I have observations and questions about mounting and dismounting them.
After upgrading from El Capitan to Mojave, the Western Digital drive started taking much longer to mount after I connected the USB cable. Under El Capitan, it would take about three seconds for the volumes’ icons to appear on the desktop. Under Mojave, it takes from five to 100 seconds (yes, I’ve timed it) for the volumes’ icons to appear. I assumed that the operating system polled the USB less frequently. However, the Samsung, which I have only used with Mojave, routinely takes about three seconds. As I typed this, it occurred to me that the difference might be the format: HFS for the Western Digital and APFS for the Samsung. Does this make sense? If so, is there a drawback to formatting the Western Digital with APFS? Might there be some other cause?
Each disk has something that I call pilot lights, for lack of a better term. On the Western Digital, it is a row of lights that flicker back and forth like a Cylon from Battlestar Galactica. On the Samsung, there is a red light and there is a blue light; I believe either can be bright or dim, but I’m not sure. When I dismount either drive’s volumes shortly after a restart (maybe one to three days), all the lights go out on the dismounted drive. After a few days, they don’t. In particular, the Western Digital will leave one light on, and the Samsung will leave the blue light on dimly. Does this mean anything? Why would the behavior change?
A perhaps related issue is the Western Digital will flash the Cylon light sequence after the volumes’ icons disappear from the desktop, as if something is still being read or written. Why wouldn’t the OS leave the icons on the desktop until all disk access has been completed?
Thanks for any insight.