My server had 7x2Tb WD Green (EARS/EARX) HDDs. I selected them because they were cheap and supposedly power saving. However this was a mistake, as I have found out the hard way, now that 4+ have died in the past year. Apparently these drives have a firmware ‘feature’ that parks the heads on the drives after 8 seconds of inactivity. EIGHT SECONDS. Which means these drives are certainly NOT suited to a NAS / storage pool setup or OS partition since wear on the disk will be large. They are really only useful as backup drives that don’t get used much. Supposedly you can use wdidle3.exe from Western Digital to increase or disable this 8 second timeout, but I haven’t tried it yet. Instead I’ve been replacing failing drives with Hitachi Deskstar drives, which from my recent research, may last 3+ years as opposed to 1.5 years max lifespan for WD green drives. I also bought 3x2Tb Seagate Barracuda HDDs as backup drives, and 1 of those 3 failed within the first year.
So, here’s my advice: If you want your drive to last more than 1.5 years before failing, don’t buy Seagate Barracuda or WD green drives.
UPDATE: I just noticed that the WD-EAR drives are running hotter than Hitachi, a good indicator for Hitachi so far: