System has started intermittently chirping every now and again when files are being written to it steadily. There is no sequence or timing to the chirping. It is NOT Beeping but Chirping. We are a computer company and we have several of these units and we know how units are supposed to work. This is not normal even though all information in the unit states all is good with the drives.
Hi @Randem,
Please refer to the article of How To Tell If The Noise or Sound An Internal Drive Makes is Normal:
https://support-en.wd.com/app/answers/detail/a_id/16309
Also please check drive health by using the dashboard.
Hi, We have checked the drive health and the S.M.A.R.T status and all was fine. This is the reason I asked the question was to see if someone knew something about this device that we did not know and was not in the documentation. One drive ending up failing and we replaced it. The problem was that one of the 4 drives was failing and the only sign was the short chirping. We did not know if it were one of the drives or the device itself. Some devices chirp to indicate a certain issue not necessarily a hard drive failure. Thanks for your response.
I would guess a fan or a spinning disk
some power supplies and electronic can have a coil whine noise,
I never saw a buzzer in the few WD NAS I took apart.
I have seen a crickets and a wasp in electronics devices 
UPS system make a chip if there is a quick power loss
Try and record the sound
I took we weeks to track a small chirp that turned out to be a weekly test sound from the Nest smoke alarm.
As mentioned it was one of the 4 drives that was about to fail but showed a good status in all tests.
