Chosen Solution
I have had this problem on a number of TimeMachine external 2.5 USB drives and I have set the System to not attempt to Put disks to sleep and disabled Power Nap. It mostly happens with the Mac Laptops. Frustrating to both my clients and me. Help!
Your HDD’s likely are pulling too much power for the USB-A ports of your systems. Many drives offered a dual plug cable so you could bank both ports power for the drive. Banging or dropping the drive won’t help and age is a factor for HDD’s as the bearings do wear out.
