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Systems and methods for accessing and updating distributed data

  • US 7,917,474 B2
  • Filed: 10/21/2005
  • Issued: 03/29/2011
  • Est. Priority Date: 10/21/2005
  • Status: Active Grant
First Claim
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1. A computer-implemented method of maintaining protection levels for nodes of a distributed mirrored indexed tree while modifying data stored in the nodes, the method comprising:

  • receiving a request to modify a target node of a mirrored index data structure organized in a hierarchy and stored among a plurality of storage devices, the mirrored index data structure comprising;

    a root node;

    at least one copy of the root node, wherein the root node and the copy of the root node are stored on different storage devices;

    a plurality of nodes beneath the root node in the hierarchy, each of the nodes referencing one or more index nodes or indexed data, the plurality of nodes including the target node; and

    at least one copy of each node of the plurality of nodes stored on one of the plurality of storage devices, wherein each node of the plurality of nodes and its respective copy are stored on different storage devices;

    accessing, by a computer processor, a first reference to the target node and a second reference to a copy of the target node, the first reference and the second reference stored on a parent node of the target node, wherein the parent node is the root node or one of the plurality of nodes and is above the target node in the hierarchy, wherein the target node is stored on a first storage device of a plurality of storage devices, the copy of the target node is stored on a second storage device of the plurality of storage devices, the second storage device different from the first storage device;

    determining, by a computer processor, whether the second storage device storing the copy of the target node is unavailable;

    accessing, by a computer processor, the target node;

    modifying, by a computer processor, the target node based on the request;

    if the second storage device is unavailable, storing, by a computer processor, a copy of the modified target node on a third storage device of the plurality of storage devices, wherein the third storage device is available and is different from the first storage device and the second storage device, and updating, by a computer processor, the second reference; and

    if the second storage device is available, updating, by a computer processor, the copy of the target node.

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