I had posted earlier about WD Green drives. Replies assured me that these drives are fine. But in my case, out of 5 WD Green (WD 20EARS) drives, 2 failed, but 3 are fine.
I started my Drobo with 4x 2TB WD 20EARS drives filled from top down. When one of the drives failed I replaced it with another of the same model.
When another failed, I replaced it with a Seagate Barracuda LP. That worked for a few hours even after the rebuild. Then after about 3 days, that showed fail as well. The failed drives, 2 WD and one Seagate all work fine in an external casing.
Anyway, I got one of the WDs replaced under warranty. They gave me a WD 20EARX drive. I put that in. All was fine for about a week. Then that failed too.
Its was then that I noticed that all three failed drives were in Slot 1, the top slot. So I’ve put the previously failed drive in the bottom slot to check it out.
My Drobo S is connected over Firewire 800 to an iMac 27" running MacOSX 10.6.6. And there’s UPS to both. I always shutdown from the Tools in Drobo Dashboard. And all the drives I’ve mentioned are 2 TB.