The following are the benchmark test results for both drives. The Green drive is on the left and the Black is on the right.
|File Benchmark Results|
|Random Access Results|
|Other Test Results|
I ran Exchange 2010 JetStress on each drive to get an accurate IOPS profile for Exchange 2010 SP2 use. JetStress was configured for a two-hour test using a single 1TB database and one thread.
- The Green drive achieved 47.396 IOPS with 10.751ms latency.
- The Black drive achieved 64.57 IOPS with 15.180 latency.
I'm not sure why the Black drive's latency was higher than the Green, given the benchmark tests above, but I ran that test twice and got the same results each time. Even so, the Black drive delivered 26.6% more IOPS.
Green Drive1.10 KW at 27.5 hours
Energy use per hour = (1.1 KWH)/(27.5 hours) = 0.04 KWH per hour of use
Energy use per day = (0.04 KWH/hour)(24 hours/day) = 0.96 KWH over a full day
Cost per day = (0.96 KWH)(18.5 cents/KWH) = 17.8 cents per day
Energy use per year = (0.96 KWH/day)(365 days/year) = 350 KWH/year
Cost per year = (350 KWH/year)(18.5 cents/KWH) = $64.82 per year.
350 KWH = ~700 lbs of greenhouse gas to the atmosphere per year.
Black Drive0.72 at 14.75 hours
Energy use per hour = (0.72 KWH)/(14.75 hours) = 0.049 KWH per hour of use
Energy use per day = (0.049 KWH/hour)(24 hours/day) = 1.18 KWH over a full day
Cost per day = (1.18 KWH)(18.5 cents/KWH) = 21.83 cents per day
Energy use per year = (1.18 KWH/day)(365 days/year) = 431 KWH/year
Cost per year = (431 KWH/year)(18.5 cents/KWH) = $79.74 per year.
431 KWH = ~860 lbs of greenhouse gas to the atmosphere per year.
Result: The WDC Green drive uses 18.8% less energy than the Black drive.
It's obvious from the test results above that the Western Digital Caviar Black drive performs better than the Green drive. At the time of this writing the Green drive costs $139 and the Black is $249. That's a 44% premium for a drive that performs on average 24% better.
In real-life observations I don't really see that much difference in performance between the two at this time. However, this Hyper-V server has twice as much RAM as my last server so it will potentially be hosting many more VMs (and will have a higher IO load). For this reason I decided to keep the Black drive, even though it costs more, it's a bit noisier when it's working hard and uses more energy. I like muscle cars, too. :)
If you plan to do RAID, I would most definitely recommend the Black drive because it spins at a consistent 7200 RPM. Reports say that the variable RPMs on the Green drive can cause read/write errors.
I hope you find this information useful.