Which HDD to use?

Quite a while ago WD released a new line of disk, WD Red drive. These drives are designed for NAS which includes features that are beneficial to RAID setup. So is Red drive the choice?

The key differences between WD Green/Red drives and Seagate Barracuda drives is the RPM and power consumption. RPM of the drives refers to how fast the platter is spinning. This rate of spinning have a direct impact on the latency and data transfer rate. Average latency of a 5400 rpm HDD is 5.55 ms, and 7200 rpm HDD is 4.16 ms.

Here is the RPM of each drive:
WD Green - Variable
WD Red - Variable
Seagate Barracuda - 7200

Some websites stated that WD Green/Red drives operate at 5400 rpm, which is not entirely true. To be more precise, the drives operate between 5400 rpm to 7200 rpm depending on usage. For a home NAS, time is not very critical, we can afford to wait for a little longer, 1 ms, right? So I think the RPM doesn't really matter much to us. Next, power rating.

Here is the power rating for 3TB drives from WD and Seagate website:

Idle:
WD Green -5.5 Watt
WD Red - 4.1 Watt
Seagate Barracuda - 5.8 Watt

Load:
WD Green -6 Watt
WD Red - 4.4 Watt
Seagate Barracuda - 8 Watt


Barracuda uses more power than Green/Red, this could be due to the RPM. Comparing Red with Barracuda on a 5 drive NAS setup, we are talking about 8.5 Watt at idle and 18 Watt at load differences. Red drives is clearly greenest among the three, even more "Green" than the Green drives.

For our ZFS setup, I doubt there will be significant difference in performance between the three drive. Red drives more expansive than Green drives but it has additional 1 year warranty and consume less power. Economically, Green drives are better, environmentally, Red drives are better. I would recommend Green drives even thought it only has a slightly higher power consumption.