Disk Failure Detected...

So i have been running into the exact same issues, error logs and lack of solid evidence showing that the disks are bad.
However, im not running Netgear at all. I created my own Linux based NAS solution (based on some specs of commercial NAS solutions).

Hardware specs:
Supermicro X7SPA-H-D525 integrated D525 processor
Intel® ICH9R Express Chipset
4 x 2 TB ST2000DL003-9VT1 disks
Raid 5

I have had two failures in the past 3 weeks, and in both situations, I could shutdown the box, re-insert the disk and start it up again.
This would trigger a resync and everything looks fine.
Other sites I have read have made the following recomendataions:
Try new SATA cables
Try a more powerfull power supply (this wouldnt apply for Netgear users)
Try new disks
Check for overheating

I have been monitoring the heat of the disks, and all 4 are below 40 deg C (within appropreate ranges).

Another site mentioned that each disk would fail once, and only once. So once they all failed for the first time, you should not see any more issues.

My take on all this...
Switching disks would probably fix this issue. Since these disks are classified as "low power/green" disks, it could be that under increased stress, the disks dont draw enough power to compensate causing a temporary hardware failure in the drive. Future smart and manufacturer test don't stress the power of the disk the same way.

So if it continues, I will buy new SATA cables... if it still continues, I will buy new drives...