Abstract: In the environment of cloud computing,faults have become a normal behavior and the shortage of reliability safeguard not only has become the main obstacle of application promotions in cloud computing,but also has made fault tolerance services in cloud computing become a problem that need to be solved urgently.Aiming at solving the shortage study of fault tolerance services in cloud computing that the definition of user fault tolerance requirements can’t reflect reliability which was concerned by the users directly and the inflexible usage of the resources of cloud fault tolerance service providers,this paper proposed an adaption method of cloud fault tolerance services which was based on user requirement and resource constriction.This paper first defined the fault tolerance requirements of users from the prospective of users,which was conducted by taking a component as a unit and reliability as a basis.Then the optimal adaption method of fault tolerance services was studied from the perspective of cloud fault tolerance services providers under the condition of that the resources of fault tolerance service providers is insufficient or sufficient.This paper solved the fault tolerance services generated by the optimal adaption method using optimization theory.The results of the experiments showed that the fault tolerance services which were generated by our adaption method can better satisfy the requirements of users and cloud fault tolerance service providers.

Key words: Cloud computing,Fault tolerance as a service,Replication fault tolerance,Checkpoint fault tolerance,Optimization