Implementation of file fault tolerance is the key for preventing data loss in cloud. However, cloud storage service providers may not offer the committed level, which results in that users may suffer data loss and economic loss. Existing inspection algorithms of testing of data fault tolerance in cloud have disadvantages such as spoofing attack of pre-fetch, low efficiency and poor practicality, which can not detect the foulbehavior of cloud storage providers within a certain probability. To deal with the above problems, utilizing the difference of sequential access and random access, a remote testing algorithm of data fault tolerance in cloud named (Difference of Random and Sequential access Time) (DRST) is designed. The core idea is that the time of reading blocks of a file stored in order on a disk is much shorter than reading blocks of a file stored random on different disks. A strict theoretical proof and a in-depth performance analysis to the proposed scheme are carried out. The results show that the proposed scheme can accurately detect whether the cloud storage provider supplies clients with the committed level of fault tolerance.What’s more, the proposed scheme is much more efficient than the existing ones.%云存储中，防止数据丢失的关键是实现文件容错。然而，云存储服务商可能没有提供承诺的容错水平，导致用户蒙受数据丢失和经济损失的双重风险。现有云存储数据容错存储方式检验方法存在服务器预读取欺骗攻击，并且效率低、实用性差，不能达到在一定概率范围内，快速、轻量级地检测出犯规的服务器行为的要求。针对上述问题，该文利用磁盘顺序存取和随机存取的差异性设计了一种远程数据容错存储方式检验方法随机与顺序访问时间差异化(DRST)方法，其原理是文件块被分散地放在不同磁盘上，读取一个磁盘上顺序存储的文件块比随机读取不同磁盘上的文件块所需的响应时间短。最后，对所提方法进行了严格的理论证明和深入的性能分析，结果表明，所提方法能够快速检验出服务器是否为用户提供了其承诺的容错水平，并且比现有方案更安全，更高效。
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