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A Block-Based Network File System

A. McGregor and J. Cleary
Department of Computer Science,
University of Waikato,,



Currently most distributed file systems transfer messages about files between machines. The implementation of file system that uses a lower level, communications interface (BB-NFS) is described. This system uses a `block-based' interface that exchanges information about the blocks that make up the file but not about the files themselves. It provides the Unix file system interface and demonstrates the feasibility and implementability of the block-based approach.

The advantages of this approach include a reduction of the processing required at the server, uniformity in managing file blocks and fine-grained placement and replication of data. The simple communications model also lends itself to efficient implementation both at the server and in the communications protocols that support the interface. These advantages come at the cost of a more complex client implementation and the need for a lower level consistency mechanism.

Leases are used to maintain consistency of file system meta-data, a lease cache is used to improve performance.

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Philip Tree