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Access control in a flash storage system

  • US 10,296,469 B1
  • Filed: 07/24/2014
  • Issued: 05/21/2019
  • Est. Priority Date: 07/24/2014
  • Status: Active Grant
First Claim
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1. A storage system comprising:

  • a plurality of storage controllers configured to couple to one or more client computer systems via one or more data communications links; and

    one or more storage devices coupled to the plurality of storage controllers;

    wherein a first storage controller of the plurality of storage controllers is configured to;

    generate heartbeats on intervals of a first period of time;

    responsive to generating a current heartbeat, issue a lease based on an extension calculated from a prior heartbeat;

    determine that a lease is invalid based on the lease extension calculated from the prior heartbeat being smaller than a takeover window calculated from the prior heartbeat;

    responsive to determining that the lease is invalid, operate as a secondary storage controller instead of a primary storage controller, wherein the first storage controller, operating as the secondary storage controller, is not allowed to perform a state-changing operation on the one or more storage devices;

    determine that the lease is valid based on the lease extension not being smaller than the takeover window; and

    responsive to determining that the lease is valid, perform a number of pending state-changing operations, wherein the number is less than or equal to a maximum number of state-changing operations that can be performed without causing data loss due to a failure of a fencing mechanism;

    recheck if the lease is valid responsive to performing the number of pending state-changing operations; and

    perform a second number of state-changing operations responsive to determining the lease is valid, wherein the second number is less than or equal to the maximum number.

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