D5-300 Buzzing all day

[Bubbatron]

My D5-300 is about 2.5 years old. Recently it has started doing something odd.
It buzzes.
It is connected to a laptop. When the laptop is idle, the D5 starts seeking like crazy. It makes a deep buzzing sound for a few seconds, then makes a deeper buzz. Repeat. All day.
What does it sound like? An old pop song. Play the start of Don Henley's "All she wants to do is dance" and listen for the bass line in the hook. That's what the D5-300 sounds like.
https://www.youtube.com/watch?v=d5p7v7XKxTw
If you move the mouse or otherwise wake up the laptop, the noise stops immediately. This tells me that it's responding to a request. It seems to be doing something in its spare time. Defragging perhaps?
Is this normal?
If the D5 is in danger of failing, please let me know immediately. It would take days to copy everything to a new RAID.
This is a RAID 5 configuration(4TBx4).
Thanks!

[TMroy]

hi Bubbatron,
We will study your case, and come back to you soon.

[TMroy]

It seams the RAID manager keep reading your device, close the RAID manager from your computer.