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Method and system for migrating data between flash memory devices

  • US 9,519,577 B2
  • Filed: 08/27/2014
  • Issued: 12/13/2016
  • Est. Priority Date: 09/03/2013
  • Status: Active Grant
First Claim
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1. A method of managing a storage system that comprises a storage controller and a plurality of flash memory devices, each with a plurality of flash memory blocks, the method comprising:

  • at the storage controller;

    dividing each of the plurality of flash memory devices into a plurality of logical chunks, wherein each logical chunk includes one or more flash memory blocks;

    detecting failure of a number of flash memory blocks for a respective flash memory device of the plurality of flash memory devices, wherein each flash memory block is the minimum size erasable unit of a respective flash memory device in the plurality of flash memory devices;

    in accordance with a determination that the number of failed flash memory blocks satisfies a predefined threshold for the respective flash memory device, performing a migration process that includes;

    selecting one of the plurality of logical chunks of the respective flash memory device for migration in accordance with predefined selection criteria;

    storing a replicated logical chunk, comprising a copy of the selected logical chunk, at a second flash memory device different from the respective flash memory device;

    remapping an address of the selected logical chunk to a physical location of the replicated logical chunk; and

    decreasing a number of logical chunks associated with the respective flash memory device, resulting in a reduced, non-zero number of logical chunks associated with the respective flash memory device;

    wherein, upon completion of the migration process, logical chunks of the plurality of logical chunks, other than the selected one, continue to be stored by the respective flash memory device.

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