The Design And Inplementation Of An Availability Evaluation Tool Based On Fault Injecting In Scsi

With the development of information technology, The change from computing centered and network centered era to storage centered era is comming. While enjoying the benefit of the massive storage system, how to evaluate its performance and availability in practical use is a core problem to solve. Fault injection is a promising method to this problem, which evaluate the system's total performance by accelerating the advent of faults. The existing fault injection method is not appropriate to evaluate the massive storage system, because of its high I/O bandwidth, high concurrence and huge capacity.In this paper, the author define the fault model for mass storage system, design and implement a fault injection tool base on SCSI. The tool intercepts the SCSI commands from upper layer and modifies the commands, then pass them to the lower layer. Through modifying the commands, many faults both transient and permanent can be injected. The comparison of performance before and after fault injection reveals the computing availability of the target system.Applying this faults injection tool to a massive storage system based on SAN architecture, and using the IOZONE tool to collect performance index of the target system, Experiment results validate the effectiveness of the tool, and give the computing availability of the system.