November 16, 2010
This entry is one in a series of Top 10 lessons learned by Ron Potter in his previous job as the Director of Capacity Planning at a Fortune 100 health insurance provider.
How to find your capacity "tipping point"
No matter what you do, you will always have unforeseen events that will drive IT systems crazy. It will be that way until Murphy's Law is finally repealed. Few organizations can afford to cover every eventuality. It just isn't economically feasible. That's where we come in. Our job is to balance cost, availability and performance.
I believe the best balance is attained through part art and part science. The science part looks at captured data to determine what has occurred in the past. That doesn't mean that planning for those peaks will mitigate the risk, it just means it will mitigate today's known risk. Tomorrow's peak may be higher because Murphy seems to know when you add capacity.
Then the art part comes into play. That involves talking to the people who suffered during those peaks. It permits you to compare different events to determine to what level and severity parts of the organization were impacted. Those discussions help you determine the "tipping point" or point where the level of "pain" on the business becomes intolerable. Your first goal should be to build a capacity plan that satisfies volumes just below that point. Cost the results out. Too high? Reduce the solution until the costs are affordable. The amount of capacity shortfall between the "tipping point" and your solution is your risk. Now go back through historical data and see how many times systems have reached the risk level. Frequently? Maybe time to escalate to management. If you do, you have the data and user experiences to back your recommendations.
Until the next post...