November 2, 2009
Whether your Web-based business is measured by your revenue per user or per transaction, knowing your detailed costs is critical to the success of your company. But do you truly know your cost per user or your cost per transaction? My bet is that you don’t.
The reason? The “money pit” of power costs.
Most people, if they know their total data center costs, treat power as a fixed cost. It’s pretty easy to set your budget for power. You generally know what you are going to spend each month: the bill comes in; you pay it. Over time as your user base grows and you add more equipment to your data center, your power bill goes up. But how do you assign power cost for each user, or each transaction, or, for that matter, each click? For each application or service, do you truly know how profitable (or unprofitable!) it is if you don’t know the cost of power required to deliver it?
The problem is that your servers are built to be “always on”—they are never turned off. But what’s wrong with that, you say? After all, if you are running a news service and a plane lands in the Hudson you must be able to meet the unplanned spike in demand. Whatever your business, you can’t plan for the unknown. Therefore you leave your servers on to handle the unexpected. Because of the way servers are built, however, their power consumption doesn’t change that much with application load. While your application load may vary from 5% to 95%, the power supplies in your server maintain a relatively flat rate of consumption, varying between about 70% and 90% of their maximum load. Whether it’s the first day of the quarter or the last, or whether it’s mid-day or midnight, you continue to pay your utility to keep every server running.
But what’s the cost of supporting the night owl who is paying her bills online at 2AM? How much does it cost for a 5am ATM transaction? If you could accurately measure the cost of these individual transactions, they would be much higher than transactions taking place during the peak usage times for paying bills or visiting ATMs, because you are paying for your full capacity of servers whether there are 2 million users or 2000. Power is a fixed cost, after all. The key question is: does it have to be?
What if your actual power use went up and down along with the number of users? If your power draw could vary between 5% and 95%, just as your application load does, you could assign power costs accurately to each transaction (or click) and know your true cost per user or transaction.
Power Assure helps you determine your true costs. By “virtualizing” power, we in effect create a flexible pool of servers that turn on and off automatically along with your application load. Because power now increases or decreases with customer demand, it is relatively straightforward to assign the amount of power each user or each transaction is consuming. This gives you a much clearer picture of the true cost of an application, and therefore, its profitability.
At any time of the day, Power Assure specifies the exact number of servers you need, plus a desired safety buffer to be able to handle quick unexpected spikes. And whether demand hits the roof or drops to nothing, your power costs will go right along for the ride.
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