Importance

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Abstract

Methods and apparatus for accessing files on networked digital data processing system provide for plurality of digital data processing nodes and a storage device, e.g., a disk drive, a 'jukebox,' other mass storage device or other mapped device (collectively referred to herein after as 'disk drive' or 'storage device'). First and second ones of the nodes, which may be a client and a server node, respectively, are coupled for communication over a first communications pathway, e.g., a LAN or other network. Both the first and the second nodes are in communication coupling with the storage device over the same or different logical or physical communications pathways. A file system or other functionality in the second (server) node receives and responds to at least selected requests--e.g., file OPEN requests--from the first (client) node for access to a file on the storage device, by generating a 'lease'. The lease includes a block map or other administrative data (referred to elsewhere herein as 'meta data') for the requested file, as well as an expiry time indicating how long the administrative data is valid. Upon grant of the lease, the client node accesses the storage device using the block map or other administrative data supplied with the lease. The server node assures that this administrative data remains valid for the period of the lease, e.g., such that the client node may directly access the requested file without risk that another node (or the server itself) has changed it. Correspondingly, the client node ceases utilization of the administrative data (and, presumably, ceases at least direct access of the file) after lease expiry.

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First Claim