7310 SAS1 Disk failed in such a way that appliance reports it has been removed, no fault light--anyo

We have had two 7310 appliances each with one J4400 shelf for about two years now and we recently had the first disk failure.  This part is to be expected since when you purchase a new box it is often a couple years before the first disk failure.

But it happened that this first drive failure involved the drive failing in such a way that the first indication is an alert log entry:

The disk in slot 'HDD 5' has been removed from chassis...

Then in the BUI it is just grey for this disk. On the physical drive there is no amber fault light.