I have a software mirror with two 6TB WD Black drives, installed about 2.5-3 years ago and one is tripping SMART errors. I have considered replacing both drives.
Side note: unrelated, but to explain the software mirror, this is accomplished through Windows 10. Yes I have the ability of hardware mirroring but if I use a hardware mirror on that controller, it means I can't use AHCI I have to switch to RAID, and then I lose RAPID mode on my primary OS drive (a 1TB SSD) and RAPID mode = good, so yes I'm stuck with software mirroring. Speed isn't an issue, so the only drawback of this setup is if Windows crashes the mirror has to be error checked on next boot which on 6TB takes the better part of a work day, while any accessing of data on that drive is painfully slow (luckily Windows 10 hasn't crashed on me in a year or two.)
For my replacement drives I was looking at two options: Update: changed my options; I've heard great things about Toshiba desktop drives lately for reliability. (also cheaper!)
1. Toshiba 6TB x300 "performance" with 128MB cache.
2. Toshiba 6TB s300 "surveillance" with 256MB cache. gotta wait until march 4th for that to be released.
Wondering what the differences are in drives other than the cache; can't seem to find transfer speeds for the "performance" model, and "surveillance" model is more reliable (MTBF 1m vs. 600k hrs)... I also run some large Virtual Machines off of this volume and I wonder if the extra cache and 241MB/s (vs. ??) transfer speed specs for a "surveillance" model would be of noticeable benefit in the performance area vs. the "performance" model. indeed performance and reliability both might be in the "surveillance" drive..
Update2: Nm on the Virtual Machines, I'm going to move them to a new Samsung EVO SSD that are on sale (can't do an m2 on my board) and just keep it backed up to the data volume. maybe then this answers the question and I should go with reliability for the data volume, but no stupid me can't wait a few weeks and I ordered the x300 models anyway. yeah nevermind...