Evaluation of an Assurance System for Provision of Latest Files

J. Funasaka and M. Bito (Japan)


Mirror Server, Consistency, Proxy System, FTP


As various popular contents are available on the recent In ternet, mirror servers which provide the same contents as the master server are often deployed to reduce the con centration of accesses. However, it is difficult for a mir ror server to synchronize steadily with the master server because of irregular updates on the master server. Thus inconsistency between replicated files in the master server and those in mirror servers is often observed and it will occur more frequently in the future because of frequent se curity updates. In order to absorb this inconsistency, we have proposed an FTP proxy system which assures us pro vision of the latest version of a file and utilizes as many mirror servers as possible. However, the evaluation of the assurance has not been investigated enough. Thus we con ducted experiments to estimate the effect of the proposed system from the viewpoint of update monitoring. Through practical experiments and simulations we evaluated some monitoring schemes to assure the users of the file consis tency. We propose a new adaptive monitoring method and confirm the effect of the method.

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