IBM's x3550 was the leanest and greenest, both in terms of CPU horsepower but also power consumed. In quiescent tests, there was less than a 2-watt difference among any of the three operating systems tested in either performance or savings mode. In the active tests, the power draws stayed within that 2-watt range with the exception of when Windows Server 2008 drew 87.8 watts, compared with Suse's 79.6 watts and RHEL's 78.3 watts in our active test when the systems were tuned from performance.
The dual-quad core Dell 1950 sucked more power overall, but with more cores, it also delivers more computing power. In the quiescent tests, the test where settings were tuned for performance, Red Hat defied logic and used slightly more power than it did in the power-savings mode, but otherwise, the results followed as logic and settings expected.
The HP DL-160 didn't show dramatic behavior changes in settings in the quiescent tests, and made Windows 2008 Server a winner in the active, performance-modes test where it seemed to give its best performance.
When we tested the DL-360G5 late in the series after having difficulties with the HP DL-160G5's Windows testing, we found it behaved similarly to the Dell 1950 (which has the same number of CPUs as this bigger HP box), consuming the highest number of watts, but also doing so with the largest number of drives.
Summary
Microsoft, Red Hat, and Novell/Suse each have power savings and green initiatives that are widely publicized. Nonetheless, we were astounded by the effort we needed to undertake in order to chase down of firmware, BIOS and other updates was necessary to get real savings in the tests we conducted. Tuning servers for optimized power savings could yield better results, but would create a new painstakingly tedious server management discipline required to constantly control the deep complexities of the configuration variables involved.
We recommend that every potentially green server deployment be thoroughly checked, as each server model may or may not have the necessary BIOS settings and operating system chipset recognition features that will result in a power savings. While all of this leg work might ring true to that famous line in the Kermit the Frog song, entitled "It Ain't Easy Bein' Green," if you consider the power savings over a five-year service life, the boost to the bottom line will likely be worth the effort.
Network World is an InfoWorld affiliate. Henderson is principal researcher and Dvorak is a researcher for ExtremeLabs in Indianapolis. They can be reached at thenderson@extremelabs.com.
This story, "Linux beats Windows 2008 power-saving measures" was originally published by Network World.