中文摘要：

对分级存储系统的性能测试，需要提供真实的系统状态和有代表性的访问负载．已有的分级存储系统测试方法通过播放一段时间的文件访问请求来生成系统状态因为彻底忽略了近期未被访问的文件而与分级存储的真实场景不符，使得测试结果没有说服力．提出了一种分级存储系统性能测试工具DMStone，它使用文件系统快照生成某一时刻的系统状态，并根据后续的相邻快照之间的差异提取访问负载特征，进而生成有代表性的I／O负载．DMStone能够提供某一时刻真实的文件系统状态，涵盖了近期访问过的和长期不用的所有文件．而且，它能够保证后续文件访问的特征与真实应用场景相符合．

英文摘要：

Realistic system states and representative workloads are required to evaluate a hierarchical storage management （HSM） system. The existing method to evaluate a HSM system reconstructs system states by replaying a trace within period of time. Ignoring files not used recently, the result of this method is not convincing enough. This paper proposes DMStone, a tool for evaluating HSM systems. DMStone uses file-system snapshots to generate a system state. Furthermore, it extracts workload characteristics by comparing two contiguous snapshots and generates representative workloads. DMStone can provide a realistic file-system state, including files used recently and those not used for a long time. Moreover, it makes subsequent workloads conform to realistic system states.