An Analytic Model of Hierarchical Mass Storage Systemswith Network - Attached Storage

Network attached storage devices improve I/O performance by separating control and data paths and eliminating host intervention during data transfer. Devices are attached to a high speed network for data transfer and to a slower network for control messages. Hierarchical mass storage systems use disks to cache the most recently used les and tapes (robotic and manually mounted) to store the bulk of the les in the le system. This paper shows how queuing network models can be used to assess the performance of hierarchical mass storage systems that use network attached storage devices. The analytic model validated through simulation was used to analyze many diierent scenarios.