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Remote access agent for caching in a SAN file system

  • US 7,685,128 B2
  • Filed: 06/10/2004
  • Issued: 03/23/2010
  • Est. Priority Date: 06/10/2004
  • Status: Expired due to Fees
First Claim
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1. A method implemented in a Remote Access Agent (RAA) to store and access remotely obtained data as a copy local to a Storage Area Network (SAN), wherein said method comprises the steps of:

  • a. receiving, at said SAN, remote data from a remote source;

    said remote source external to said SAN;

    b. said SAN decoupling attributes from content in said received remote data to form decoupled attributes and decoupled content;

    c. said SAN locally storing in computer storage said decoupled attributes as metadata and a copy of said decoupled content, separately, said metadata comprising at least;

    a content storage attribute if said local copy represents a file, a directory mapping if said local copy represents a directory entry, and object attributes, said decoupled attributes being updatable by fetching attribute data from said remote source, said storage storing SAN file system contents in containers holding managed data originating from remote sources, with each container comprising one or more directories and each directory further comprises one or more files, attachment points, and symbolic links; and

    d. said SAN obtaining file-level access to said decoupled content based on said locally stored decoupled attributes only when a consistency guarantee exists for said locally stored decoupled attributes, said consistency guarantee providing assurance of metadata and file content validity and said consistency policy defining conditions for freshness check of attributes, and said consistency guarantee expiring after a pre-determined period of time, said freshness check comprising;

    triggering a check of attributes associated with a local object, checking for metadata defining a consistency guarantee for said local object, based on said checking step, fetching from said remote source attributes of a remote object associated with said local object, based on said fetching step, creating a consistency guarantee for said local object, and merging said fetched attributes with attributes already associated with said local object.

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