With the prevalence of service computing and cloud computing, more and more services are emerging on the Internet, generating huge volume of data, such as trace logs, QoS information, service relationship, etc. The overwhelming service-generated data become too large and complex to be effectively processed by traditional approaches. How to store, manage, and create values from the service-oriented big data become an important research problem. On the other hand, with the increasingly large amount of data, a single infrastructure which provides common functionality for managing and analyzing different types of service-generated big data is urgently required. To address this challenge, this paper provides an overview of service-generated big data and Big Data-as-a-Service. First, three types of service-generated big data are exploited to enhance system performance. Then, Big Data-as-a-Service, including Big Data Infrastructure-as-a-Service, Big Data Platform-as-a-Service, and Big Data Analytics Software-as-a-Service, is employed to provide common big data related services (e.g., accessing service-generated big data and data analytics results) to users to enhance efficiency and reduce cost.