Modality Cost Analysis: A Methodology for Cost Effective Datacenter Capacity Planning in the Cloud

摘要

In resource provisioning for datacenters, an important issue is how resources may be allocated to an application such that the service level agreements (SLAs) are met. Resource provisioning is usually guided by intuitive or heuristic expectation of performance and existing user model. Provisioning based on such methodology, however, usually leads to more resources than are actually necessary. While such overprovisioning may guarantee performance, this guarantee may come at a very high cost. A quantitative performance estimate may guide the provider in making informed decisions about the right level of resources, so that acceptable service performance may be provided in a cost-effective manner. A quantitative estimate of application performance must consider its workload characteristics. Due to the complex workload characteristics of commercial software, estimation of its performance and provisioning to optimize for cost is not straightforward. In this work we looked at breaking the application into isolated modalities (modality is a scenario in which an application is used, for example, instant messaging, and voice calls are two different modalities of a media application) and measuring resource cost per modality as an effective methodology to provision datacenters to optimize for performance and minimize cost. When breaking the application into modalities, resource cost is assessed in isolation. Results are then aggregated to estimate the overall resource provisioning requirements. A validation tool is used to simulate the load and validate the assumptions. This was applied to a commercially available solution and validated in a datacenter setting.