Mostly reliable over-all: 1) We have 9 of these units, at various ages, running within a Synology DS3617xs NAS box since 2019. 2) Light use, mostly cold storage, not a production server. 3) The oldest 12TB Gold 121KRYZ drive has just died, during a RAID 6 expansion, with >400 bad sector relocations. 4) This caused the RAID expansion to crash (the new drive was not incorporated into the RAID), as well as 6) The RAID-6 getting "DEGRADED" from dual to single redundancy, due to the failed old drive. The 48 hour thrashing repair/rebuild with another new drive was nerve racking, but all's good for now. but

Claiming warranty from Western Digital was a nightmare: 1) To be fair, NOT all of our drives were purchased from MemEx, the effected drive was not, so we had to deal with WD directly. 2) The number of hoops we had to jump through to get warranty from WD was beyond extreme, including having to ship the drive to them at our own bother and expense. 3) An almost entire day of our valuable time, and countless phone calls were wasted, just to get an "unpaid" RMA shipping label from WD. I seems that the once "golden" Western Digital/ HGST corporations have gone to hell in a picnic basket.

Mostly OK. Not as robust as the Gold/RE/SE drives in the old days. Western Digital warranty now sucks. !!! These drives are expensive. The customer deserves better warranty/support service.