Hello,
I’m torn between those two models, and I’m mostly concerned about noise and reliability. I will be using two of them in a mirrored RAID (actually, Synology Hybrid RAID).
From the latest Backblaze statistics, two WD Ultrastar HC550 16 TB models (WUH721816ALE6L0 and WUH721816ALE6L4) had an amazing reliability, but from the specs they are quite noisy: 2/3.6 dB. My issue is, that a lot of people say that they indeed make strange loud noises, but the same amount of people say that they are quiet.
OTOH, Seagate released the NT001 series this year (ST16000NT001, for example), were they caught up with other with the MTBF ratings, and from the specs they are quieter than the WDs: 2/2.6 dB. But they are also more expensive than the HC550s.
I will be having the Synology NAS in the living room, with BTRFS, and it will be used mostly for playing movies over WIFI, so the read speeds will be very low.
What are your experiences with these two models, concerning the noise?
All 16TB and larger drives, regardless of model/brand, are noisy. They have up to 10 spinning platters and a large arms/heads assembly that create audible vibrations.
However, the noise is very much dependent on how they are mounted. If they are screwed directly to a metal chassis or metal trays without any cushioning, the noise will resonate throughout the case, making it worse.
Most NAS cabinets should have various methods of dampening sound, but if not, cushioning drives/trays with rubber/silicon bearings can reduce noise significantly.