Computer networks--Workload

In this study, a tool has been developed which traces the storage subsystem workload at the subsystem level. Due to hardware assistance, this tool has very little overhead. This is achieved by incorporating the tracing routine in the microcode of the IBM SCSI adapter. The I/O traces are collected, in realtime, on a PS/2 connected to the modified SCSI adapter via an asynchronous link. These traces are then processed and studied. We have developed a scheme to characterize the workload by studying the parameters of the traced workload. These parameters include LBA distributions, interarrival time distribution, size distributions, ratios between read requests and write requests, adapter's cache performance, etc. In this study, workload characterization of storage subsystems in OS/2, AIX and NetWare environments was performed. An algorithm for synthesizing of the workload was also developed and implemented as part of this study.