Saturday, January 23, 2010

Control costs

The visibility and control provided by sFlow can significantly reduce data center costs, both in terms of the capital cost of equipment and the operational costs of managing, powering and cooling the data center.

Poor visibility results in significant costs in two ways:
  1. Over provisioning, because demand is poorly understood system architects act defensively, overestimating requirements and adding excessive safety margins as insurance. The excess capacity built into the system is expensive to purchase and maintain, however, since there is no visibility these costs are hidden.
  2. Poor Service, because demand is poorly understood, operational changes occur in reaction to costly service failures, resulting in rushed, poorly targeted addition of capacity that further increase wasteful over provisioning.
The network wide visibility provided by sFlow fundamentally changes the equation. Detailed visibility into demand allows resources to be targeted where they are needed, minimizing over provisioning and avoiding service failures.

The diagram graphically demonstrates the difference between these two approaches. In the case of limited visibility, the increase in demand is not detected until it is too late. Over-reacting to the performance failure leads to excessive over-provisioning. With the visibility and control provided by sFlow, the increase in demand is detected early and additional capacity added. As demand for the service decreases, the additional resources are released so that they can be applied elsewhere.

The benefit of data center convergence and virtualization is that resources are pooled and can be allocated as needed. However, without network visibility it is impossible to fully realize the cost savings and improved performance that convergence promises.

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