Not sure what drives are in there
I think the problem is the WD Whites are known to have features turned off vs their HGST counterparts despite being the same part number. Compare this with the Seagate externals which have identical retail drives placed in them. The largest Expansions have Exos in them with some reports of them even having valid warranty on the bare drive serials.There is really no need to wait for next black friday, just use a reminder service like Geizhals (DE/EU) or Camelcamelcamel.
These are solid drives and probably more reliable than Seagate retail drives. I run the 14 TB predecessors (white label HC 530) in a RAIDZ2 ZFS stack. Absolutely what ZFS was made for, to keep your data safe and recover from errors the right way.
They run at 7200 rpm even if label says "5400 rpm class". Never seen a helium 5400 rpm drive. Some need the SATA 3V-pin fix, some don't. Only thing worrying is the slow medium read/write speed compared to its size. 18,000,000 MB / 150 MB/sec = 120,000 seconds or 33 hours to fully read or write the drive. Kind of reminiscent of the Quantum Bigfoot drives of the late 1990s, only 3000 times bigger. That is some awesome progress right there, right.
These drives will not support the simple hdparm standby timer mechanism, you will need a recent hd-idle, that will work. If you run ZFS and use these drives through an LSI SAS controller in IT mode, do not put the drives into standby. ZFS will not like it and produce many errors. Also do not enable any SATA Link Power Management to save power, the drives will also not like it. If you want ZFS and also standby, you have to use mainboard SATA ports (AHCI) or if those are full get a 5-port JMB585 PCIe 3.0 card (also AHCI, get one with heatsink).
Wouldn't surprise me as it seems the current seagate enterprise lineup is akin to their flagship products of yesteryear. My 6x 16TB exos are doing great as well as the 8TB and 2TB ones I have.Could be a good sign? Since it shows that the drives aren't failing?