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Management of two-queue request structure for quality of service in disk storage systems

  • US 7,293,136 B1
  • Filed: 08/19/2005
  • Issued: 11/06/2007
  • Est. Priority Date: 08/19/2005
  • Status: Active Grant
First Claim
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1. A method of managing the queuing of storage requests to a disk drive, the storage requests being divided into high-priority requests and low-priority requests, the high-priority requests generally requiring low response time and the low-priority requests generally requiring high throughput, the high-priority requests being divided into a plurality of priorities, the method comprising:

  • placing each low-priority request on a low-priority request queue, the low-priority request queue being the subject of throughput optimization by which requests on the low-priority request queue are executed by the disk drive in a throughput-optimizing order generally different from the order in which the requests are placed on the low-priority request queue; and

    for each high-priority request;

    (i) determining whether there are more than a predetermined number n outstanding requests for execution by the disk drive having priority greater than the priority of the high priority request;

    (ii) if there are not more than n such outstanding requests, then placing the high-priority request on a high-priority request queue, the high-priority request queue being the subject of priority selection such that requests on the high-priority request queue are executed by the disk drive ahead of requests on the low-priority request queue; and

    (iii) if there are more than n such outstanding requests, then placing the high-priority request on the low priority request queue such that the high-priority request is included in the throughput optimization along with the low-priority requests on the low-priority request queue.

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