The Clouds Impact on Application Performance
The cloud's impact on application performance
In an effort to increase capacity for composite Web applications, many organizations are deploying virtualized or cloud-based infrastructures. However, much like third-party services, virtualized and cloud infrastructures can introduce new layers of complexity and the potential for performance degradation. Organizations, therefore, need to understand how virtualized and cloud-based infrastructures impact application performance, especially during times of peak traffic.
For example, just as organizations often base capacity decisions on utilization levels rather than performance, so do many virtualization vendors fail to correlate utilization to performance. IT virtualization technologies may provide CPU utilization figures, but this does not answer the central questions such as, "How many virtual instances can I create and how much load can I put on each virtual system before performance for users starts becoming unacceptable?" The answers to these questions should guide capacity decisions. When user performance gets close to the "unacceptable" threshold, it may be time to add a new virtual machine or other capacity.
Similarly, organizations need to closely consider performance issues, not just capacity, when considering a cloud service provider. Many organizations are attracted to the cloud by the promise of elasticity, which suggests that capacity will be there whenever and wherever it's needed (thus making the task of capacity management much simpler). However, cloud customers need to demand answers to questions such as, "Will this extra capacity ramp-up be fast enough so that it's invisible and seamless to my users?" and "If a 'neighbor' in my cloud environment experiences a sudden spike in traffic, how can I be sure my users won't experience a decline in performance?"