Is it normal that External Hard Drives continue to be listed in Disk Utility / diskutil even after Eject?

Question

I have an USB External Hard Drive which has been behaving strangely lately. I'm concerned, amongst other things, that it doesn't seem to Eject properly¹.

When I

• Press the Eject button in Finder;
• Eject the Volume in Disk Utility;
• Or diskutil unmountDisk in Terminal;

the drive continues to be listed in Disk Utility and diskutil list in Terminal. It is however not visible in Finder. Adding to my concerns is that the drive make mechanical sounds even after Eject.

My question is if it's normal that the drive continues to be listed in Disk Utility and diskutil even after Eject? To me it seems strange, but perhaps it's intentional in the sense that the Volume has been unmounted but the drive is still USB-connected?

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¹What has raised my concerns about this is because the drive exhibits I/O errors when trying to backup my NAS to it. The drive is formatted in HFS+. Previously, the drive was formatted as exFAT, and the volume could then not be mounted by macOS, but Disk Utility and diskutil could list the device. At that time, the same Eject "issue" as described above occurred. It didn't feel as if it was properly ejected since I heard it making sounds, and once macOS even complained about not ejecting properly even after pressing the Eject button and seeing it become grayed in Finder.

Answer 1

This is completely normal and no issue to worry about.

When you unmount a volume you are just removing the read and write access to it but the computer knows that the HD is still connected to your computer. You can always mount it again by clicking Disk Utility and click the volume and mount it.

To make the HD disappear from the list you have to physically remove it.

The reason the disk stays in the list is so that you can mount it if required, you can't mount anything the OS can't see.