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Two-pass defragmentation of compressed hard disk data with a single data rewrite

  • US 5,574,907 A
  • Filed: 11/30/1994
  • Issued: 11/12/1996
  • Est. Priority Date: 11/30/1994
  • Status: Expired due to Term
First Claim
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1. A method for defragmenting compressed data stored in files in non-adjacent variable-length clusters on a disk having a beginning and an end, each cluster comprising at least one sector, said method comprising the steps of:

  • maintaining a first data structure having an entry for each file stored on the disk, each entry identifying the cluster in which the first portion of the file data is contained;

    maintaining a second data structure having an entry for each cluster on the disk, each entry identifying another cluster in which the next portion of the file data is contained;

    maintaining a third data structure having an entry for each cluster on the disk, each entry identifying the sectors in which the file data of each respective cluster is contained;

    rearranging the second and third data structures such that the respective entries for each file are located in adjacent clusters starting from the beginning of the disk;

    updating the first data structure entries as necessary responsive to said step of rearranging the second and third data structures; and

    rearranging the file data on the disk such that the file data is located in adjacent clusters as determined by the rearranged second and third data structures;

    wherein file data is not moved during said step of rearranging the second and third data structures.

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