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Efficiently managing unmapped blocks to extend life of solid state drive

  • US 9,946,473 B2
  • Filed: 05/17/2016
  • Issued: 04/17/2018
  • Est. Priority Date: 12/03/2015
  • Status: Active Grant
First Claim
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1. A method of managing a storage device that includes non-volatile memory, the method comprising:

  • receiving write commands from a host system;

    determining a quantity of storage units in the storage device that are unmapped;

    operating the storage device in a mode of operation that is a first mode of operation while the quantity of storage units in the storage device that are unmapped satisfies a first threshold regardless of a level of overprovisioning in the storage device, wherein the quantity of storage units that are unmapped comprises unmapped storage units in a declared storage capacity and in over-provisioning space of the storage device;

    changing the mode of operation of the storage device to a second mode of operation in accordance with a determination that the quantity of storage units in the storage device that are unmapped does not satisfy the first threshold;

    while operating the storage device in the second mode of operation, for each write command received from the host system;

    determining whether processing the write command would reduce the quantity of storage units in the storage device that are unmapped to a quantity less than a second threshold;

    in accordance with a determination that processing the write command would not reduce the quantity of storage units in the storage device that are unmapped to a quantity less than the second threshold, accepting and processing the write command from the host system; and

    in accordance with a determination that processing the write command would reduce the quantity of storage units in the storage device that are unmapped to a quantity less than the second threshold, forgoing acceptance and processing of the write command from the host system.

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