This is a Dell T110 II running Windows Server 2008 R2 with PERC S100/S300 RAID 5.
One of the HDDs was taken out of the 3-skik array and is now running DEGRADED.
I removed the old HDD and replaced it with a new on IN THE SAME SLOT.
The new one has been identified as an SSD!!
I can't proceed as an SSD is "the wrong kind of drive" to be brought into the array.
In view of the slot ID, the simple-minded BIOS, etc. this can't be a BIOS issue.
Somewhere I read about this being a driver issue but I can't find the reference.
No matter what, I need to preserve this system as it's in production.
I can work on it over the weekend but can't afford to "lose" its functionality.
So, if it's a driver issue then I have to be convinced that whatever is recommended won't blow away the array which is still working in DEGRADED mode.