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Multiple controller sharing in a redundant storage array

  • US 5,546,535 A
  • Filed: 01/13/1995
  • Issued: 08/13/1996
  • Est. Priority Date: 03/13/1992
  • Status: Expired due to Term
First Claim
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1. A redundant data storage array system including:

  • a. a multiplicity of physical data storage units, each physical data storage unit comprising at least one logical data storage unit;

    b. at least two logical arrays, each comprising at least one logical data storage unit;

    c. at least two redundant array controllers, each corresponding to a logical array, at least one redundant array controller actively coupled to at least one physical data storage unit to which at least one other array controller is actively coupled, and each capable of accessing only the corresponding logical array unless another array controller has failed, whereupon an array controller other than the failed array controller is granted access to the logical array corresponding to the failed array controller; and

    d. means in each redundant array controller for activating a secondary event management means corresponding to a failed controller after the switch management means determines that such a failure has occurred;

    wherein each redundant array controller further includes a normally active primary event management means for controlling data flowing into and out of only the logical array corresponding to that array controller, and at least one normally dormant secondary event management means for controlling the flow of data into and out of only a logical array corresponding to another controller only after the failure of such other controller, the at least one secondary event management means becoming active only when the other controller fails, such that the primary event management means and the at least one secondary event management means share the redundant array controller that includes the primary event management means and the at least one secondary event management means;

    wherein the primary event management means is capable of accessing only the logical array corresponding to the redundant array controller, and the secondary event management means is capable of accessing only the logical array corresponding to the failed controller;

    wherein each redundant array controller includes a switch management means for determining that another array controller within the system has failed;

    wherein the switch management means receives messages from other array controllers on a periodic basis and includes a resetable timer for determining when the time between receipt of each message has exceeded a specified duration.

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