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Technique for coherent suspension of I/O operations in a RAID subsystem

  • US 7,328,364 B1
  • Filed: 03/21/2003
  • Issued: 02/05/2008
  • Est. Priority Date: 03/21/2003
  • Status: Active Grant
First Claim
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1. A method for suspending input/output (I/O) operations executed by a subsystem of a storage system, comprising:

  • constructing an I/O tree that accommodates a flow of I/O operations through the subsystem and targeted to the object;

    imposing a freeze condition on an object of a the I/O tree representing a logical configuration of storage devices coupled to the storage system;

    instantiating raidio structures used to communicate with the objects of the configuration tree, the objects having configuration interfaces defining services provided by a process of the subsystem;

    providing an I/O thread having a receive list to process the instantiated raidio structures;

    invoking accounting procedures each time a raidio structure is instantiated;

    enabling in flight I/O operations directed to the object to reach a recoverable state in the event the subsystem subsequently fails;

    blocking new I/O requests directed to the object at the subsystem until the freeze condition is lifted;

    incrementing a per-object activity counter in response to dequeuing of a raidio structure from a receive list of the I/O thread; and

    decrementing the per-object activity counter in response to completion of processing of the raidio structure.

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