Odysseas I. Pentakalos

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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 files and tapes (robotic(More)
Mass storage systems are nding greater use in scientiic computing research environments for retrieving and archiving the large volumes of data generated and manipulated by scientiic computations. This paper presents a queuing network model that can be used to carry out capacity planning studies of hierarchical mass storage systems. Measurements taken on a(More)
1 Abstract| Mass storage systems are nding greater use in scientiic computing research environments for retrieving and archiving the large volumes of data generated and manipulated by scien-tiic computations. This paper presents a queuing network model that can be used to carry out capacity planning studies of the Unitree mass storage system. Measurements(More)
This paper presents results of preliminary work concerning the analytical modeling of a robotic tape library using stochastic automata. This model is a rst approximation which we use to test the eeciency and accuracy of stochastic automata networks as a modeling tool. The eeects of interactive get and put requests, migration, and purging at online and(More)
A Unix based mass storage le system which provides access to the stored data only through the ftp protocol has provided the incentive to examine the performance of inserting an online data compression algorithm at each client in order to increase the eeective capacity of the storage system. Two online compression algorithms were tested, namely the(More)
SUMMARY The constant growth on the demands imposed on hierarchical mass storage systems creates a need for frequent reconnguration and upgrading to ensure that the response times and other performance metrics are within the desired service levels. This paper describes the design and operation of two tools, Pythia and Pythia/WK, that assist system managers(More)
Information management is an important area to concentrate for the business continuity of an organization. Organization should have a plan to store, retrieve and maintain its valuable information to meet the business demands. Storage Area Network (SAN) is a high performance network available to meet the enterprise storage solution. Since, SAN uses Fibre 1 /(More)