We know there has been a lot of work done or being done to make customers attract and adopt virtualization to make the environment green. To augment that, the upcoming release of Microsoft's Windows 2008 R2 has some nifty "green" features which is really a good step to narrow the gap of green characteristics between software and hardware.

You probably have heard about processors with "multicores" where a single physical processor internally has dual or quad cores presented to the OS as multiple "logical" processors. In a normal scenario once the OS is installed, all the cores are active and start consuming power which could be a huge waste of resources if the application doesn't need that much computing power. So, wouldn't it be nice if we have a way to control this behavior somehow by making the cores "active" or "inactive". The upcoming release of Windows Server 2008 R2 gives you just that capability and some additional ones. The following OS features improve reduce power consumption:

• Reduced multicore processor power consumption
• Reduced processor power consumption by adjusting processor speed
• Reduced storage power consumption

Reduced multicore processor power consumption

This feature itself is called as "Core Parking" and allows Windows Server 2008 R2 to consolidate processing onto the fewest number of possible processor core and suspend inactive processor cores, as show in the figure below.

If additional processing power is required, the "Core Parking" feature activates inactive processor cores "automatically" to handle the increased processing requirements. Needless to say, a new feature with "automation" to turn ON and OFF the heart of the computer needs to be watched out as it may indirectly affect the application response and performance if not activated on time. So, I'm not so sure what to say here as I haven't witnessed the feature yet. Only MS can shed some light whether we can close our eyes and trust them that it really "works" :-). Anyway, I would try to get this clarified by MS folks with some good explanation to back the feature. So, watch out this space for more updates.

Reduced processor power consumption by adjusting processor speed

The second one on the list is the feature with an ability to adjust the ACPI "P-states" of processors and architecture. Windows Server 2008 R2 can adjust the "P-states" of individual processors and provide very fine control over power consumption as shown in the figure below:

One may ask, why would I really need to mess-up with the p-states on the processor cores to have them run on two different frequencies? Well, if you are really looking at ways to reduce your power consumption and looking to calculate an ROI out of it, then you got to do it. MS has given you some options to poke around with, and you need to go and figure to make the best use of it for your requirements.

Reduced storage power consumption

Have we ever thought about buying "diskless" servers yet? may be some folks did, but majority of us still buy servers with local storage. Diskless computing reminds me of those Novell days where all the nodes used to boot from a central server and things used to work well. All of sudden industry took a turn and we moved to decentralized computing, killing "centralized" approach completely. Now, after decades, we are talking about it again, sort of having "old wine in a new bottle". And that is precisely the third option - "Reduced Storage Power Consumption". Today many medium to large businesses have some kind of SAN storage in place, but they still buy servers with local storage. Why not we stop buying servers with local hard drives in it and make use of SAN instead to boot the OS? Booting the OS from SAN approach would give you a substantial amount of savings on power consumption. So, MS is asking customers to make use of Windows Server 2008 diskless boot from SAN feature to reduce the carbon footprint.

Now, the million dollar question is, "How do I make use and set options 1 or 2 in my environment?"

Answer: "Use Active Directory Group Policy Settings"

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