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Apparatus and method for extending the useful life of a data storage system

  • US 6,000,021 A
  • Filed: 02/19/1997
  • Issued: 12/07/1999
  • Est. Priority Date: 02/23/1996
  • Status: Expired due to Fees
First Claim
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1. Apparatus for extending the useful life of a data storage system having components subject to wear, the components subject to wear being read/write members and storage areas of a storage medium, data being read and written in the storage medium by the read/write members performing access operations on respective storage areas, the access operations imposing wear on the components subject to wear, the apparatus comprising:

  • a memory in which is stored an address correction table that assigns physical addresses of the storage areas to logical addresses;

    a counter that registers an access count for each of the components subject to wear;

    data exchange means, operating in response to the access count for one of the components subject to wear reaching a first threshold value, for performing a data exchange operation in which data stored in a first storage area are exchanged with data stored in a second storage area,the first storage area being the one of the storage areas having the access count that reached the first threshold value and the second storage area being one of the storage areas having an access count less than the first threshold value when the components subject to wear are the storage areas,the first storage area being the one of the storage areas accessed by the one of the read/write members having the access count that reached the first threshold value and the second storage area being one of the storage areas accessed by another of the read/write members having an access count less than the first threshold value when the components subject to wear are the read/write members;

    means, operating after each data exchange operation, for rewriting part of the address correction table to assign the physical addresses of the second and first storage areas after the data exchange operation to logical addresses that correspond to the physical addresses of the first and second storage areas, respectively, before the data exchange operation, andmeans, operating in response to the counter, for identifying ones of the components subject to wear having an access count less than a second threshold value, the second threshold value being less than the first threshold value;

    in which,the second storage area on which the data exchange means performs the data exchange operation is one of the storage areas having the access count less than the second threshold value when the components subject to wear are the storage areas and is the one of the storage areas accessed by one of the read/write members having the access count less than the second threshold value when the components subject to wear are the read/write members.

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