Using ZFS myself and lots of reports of btrfs having the same issue on the WD thread. My two 8TB Gold drives are a mirrored pair alongside another mirrored 4TB

Using ZFS myself and lots of reports of btrfs having the same issue on the WD thread. My two 8TB Gold drives are a mirrored pair alongside another mirrored 4TB pair of WD Reds from a few years back, which don't exhibit the same issue. It's such a weird sound for a modern drive to make - it's like a printer spooling paper mixed with a floppy drive. One suggestion on the thread was that the disk was doing some sort of lifespan optimisation when idling, which might make sense, as it never makes the noise when under load. Mine are even louder than that clip above, I can actually hear it across a room. Guess I'll be sound insulating a data cabinet to cut it down a bit!