You have to survey the closet articles to your (keyword &problem statement) in order to know which data set they used. due to the data set importantly to be identified.   

Thanks for your reply. But in related studies they setup their own environment and they measure the QoS attributes and none of them have published their data sets. I have posted here after carrying out an extensive search. 

The collection of QoS related data is often a task of the company IT Services and majority of clients are not really aware of how the data are collected. However, they are quite concern with their perception of QoS provision and often are quite critical  and not content. Given the complexity and vulnerability of the Cloud today, the Cyber Security has become the essential part of User's Perception. However, no exact metric have been established yet on how to measure QoS Provision side by side with the Security Assurance.

@Eduard Babulak Thanks for your reply. Sir I totally agree that customers are not aware of measuring and/or evaluating the QoS attributes and it is the responsibility of IT services to make arrangements to asses the service quality. But what do you suggest for experimental purposes? I am planning to use a cloud simulator to evaluate QoS.