With the fast growth of (online) content and the need for high quality content services, cloud data centers are increasingly becoming the preferred places to store data and retrieve it from. With a highly variable network traffic and limited resources, efficient server selection and data transfer rate allocation mechanisms become necessary. However, current approaches rely on random server selection schemes and inefficient data transmission rate control mechanisms. In this paper we present SCDA, an efficient server selection, resource allocation and enforcement mechanism with many salient features. SCDA has prioritized rate allocation mechanism to satisfy different service level agreements (SLA)s on throughput and delays. The allocation scheme can achieve max/min fairness. SCDA has a mechanism to detect and hence mitigate SLA violation in realtime. We have implemented SCDA in the NS2 simulator. Extensive experimental results confirm some of the design goals of SCDA to obtain a lower content transfer time and a higher throughput. The design of SCDA can achieve a content transfer time which is about 50% lower than the existing schemes and a throughput which is higher than existing approaches by upto than 60%.