Strange noise coming from 10TB drives (WD100EFAX)

I’m having this issue with 4x 8TB WD Red Pro Drives 256 Mb (WD8003FFBX-68B9AN0) in a Synology DS918+ NAS, using SHR-1 and btrfs. See my old thread below and a video clip in it:

Note of particular interest that the green lights on the NAS freeze when the beeping noise occurs. I have no clue if I’m right, but doesn’t it appear like operations momentarily cease?

I contacted Western Digital’s support back in December, and after some conversation with them, they told me that the beeping noise isn’t normal and that I could RMA the drives. However, I became busy with other things and time went. After a while, I realized that the beeping noise had gone away – only to return a few days ago.

It then recurred over the course of maybe 1–2 hours before going away. I still the option of RMAing the drives, but I’m really interested in understanding if this is a problem with a drive or not. I could of course follow WD Support’s suggestion to simply RMA them, but from what I’ve read before sometimes they just tell people to RMA instead of actually being specific on there being a problem or not. I guess that has both positive and negative sides.

Btw, the drives are also doing a few other noises that seem related to the “beeping” sound. Two noises in the clip below, a “rev up” spinning sound in the background, and also a sudden rasping/aggressive sound – both occur at the very start of the clip. This usually occurs when starting a process like backup. However, the sudden raspy/intense sound can happen almost anytime, and pops out compared to normal operation sounds.

Audio clip: Vocaroo | Online voice recorder