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Method and apparatus using address and read head location information to provide optimal operation of a disk system

  • US 5,708,793 A
  • Filed: 03/31/1995
  • Issued: 01/13/1998
  • Est. Priority Date: 03/31/1995
  • Status: Expired due to Fees
First Claim
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1. In a computer system including a host system and a disk system with a plurality of cylinders each having a plurality of tracks with each track containing a plurality of blocks arranged in stripes within each cylinder, a method of operation comprising:

  • a) establishing a utilization level U by providing a number of logical block addresses for the disk system whih is less than the actual number of addressable physical blocks in the disk system;

    b) maintaining physical blocks that are in use randomly distributed throughout the disk system;

    c) determine the cylinder C, track T and physical block B location that is being accessed and write updated data of data at location C'"'"', T'"'"', B'"'"' into the next physical block location B+1 if it is indicated as being free;

    d) write said data in physical block location B+1 in another track in the same cylinder C if block B+1 on said another track is indicated as being free and location C, T, B+1 is not free;

    e) indicated as free the previous location C'"'"', T'"'"', B'"'"', of the data that has been updated to maintain utilization of actual storage locations in the disk system substantially at U or below; and

    f) selecting the utilization level U to maintain average write acess time at less than two times the time necessary to access said next blocking by selecting a value for the utilization level U that results in 1/1-UI being <

    2 where I is the number of tracks in a cylinder.

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