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CACHING SCHEME SYNERGY FOR EXTENT MIGRATION BETWEEN TIERS OF A STORAGE SYSTEM

  • US 20120239864A1
  • Filed: 05/30/2012
  • Published: 09/20/2012
  • Est. Priority Date: 09/02/2010
  • Status: Active Grant
First Claim
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1. A method, comprising:

  • determining to move an extent from a source-tier in a storage system to a destination-tier in the storage system, wherein a set of tracks of the extent is presently being accessed;

    determining whether any track from the set of tracks is presently being written to;

    designating to a write-stack associated with the source-tier each track that is presently being written to and designating to a read-stack associated with the source-tier remaining tracks from the set of tracks;

    removing oldest tracks from the read-stack and the write-stack until the read-stack and the write-stack have been depleted of tracks;

    when a parameter of the extent exceeds a migration threshold;

    populating a destination-tier cache with the tracks as they are removed from the read-stack and the write-stack using a predetermined read-to-write ratio; and

    removing any tracks from a source-tier cache that were removed from the read-stack and the write-stack; and

    migrating the extent from the source-tier to the destination-tier.

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