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Server Consolidation

  • May 23, 2006 at 2:04 pm

    #168214

    I wrote an article on server consolidation, basically looking at the pros and cons of combining multiple instances onto one server. There are a variety of reasons why or why not to do this, but power is a good reason to consolidate. Data centers are feeling the power crunch as server densities grow and more power (and cooling) is required in the same space.

    Heck newer servers are more efficient and with the cost of fuel rising, it may make sense to upgrade your servers just to be more efficient. Heck, you may end up with a zero cost if your electricity bill falls far enough.

    One of the more interesting things with consolidation is the variety of ways in which you can do it. You can move databases onto one instance, create multiple instances, or use virtualization to install multiple Windows host servers on one physical server. These are difficult decisions to make for performance reasons, much less manageability or power reasons.

    And I wonder what the power difference is? If I run my server at 75% CPU with disks active more often, is that using more power than a server that trundles along at 10% with disks just spinning? I'd think that the heavily used server would pull more power, but perhaps not. If that's the case, then consolidation starts to make much more sense.

    Just be sure customers know they won't have the headroom they used to have and performance impacts will come more often.

    Steve Jones

  • May 25, 2006 at 4:32 am

    #639989

    Unfortunately, most CPU architectures use the same number of Watts irrespective of what they are doing. Only some modern laptops can reduce their power consumption (by dropping clock speed) depending on the load.

    Also, a server would not typically be configured with power-save options, such as stopping HDDs spinning, as this would leave a long wake-up time.

    As far as I know, an HDD uses about the same power whether it is simply idly spinning or reading/writing data. My understanding being that the vast majority of power is used by the motor to spin the discs; very little power is used to manoeuvre the heads.

    So I would think that consolidating servers would greatly reduce power consumption. Anyone out there have any facts and figures?

    Andy

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