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Method and apparatus for implementing redundancy on data stored in a disk array subsystem based on use frequency or importance of the data

  • US 6,611,897 B2
  • Filed: 04/17/2002
  • Issued: 08/26/2003
  • Est. Priority Date: 03/22/1999
  • Status: Expired due to Term
First Claim
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1. In a storage system that receives a write request for data from a host processor and stores said data on a plurality of physical disk apparatuses, said storage system includes a storage controller that receives said data write request from said host processor through a host processor interface, said storage controller dividing or segmenting said data in units of a data block to store said data in said physical disk apparatuses, a method of implementing redundancy on said data comprising the steps of:

  • determining a method for implementing redundancy based on at least one of use frequency of said data or importance of said data;

    when the method for implementing redundancy determined in the determining step is one which stores said data in both a first storage area and a second storage area to thereby duplicate said data, storing said data in said first and second storage areas such that, in said second storage area, said data are continuously stored in a same physical disk in units of a parity group, and in said first storage area, data blocks constituting a parity group are stored in a plurality of physical disks in a distributed manner; and

    when the method for implementing redundancy determined in the determining step is one which stores said data by generating parity data for a predetermined number of data blocks to thereby implement redundancy, storing said predetermined number of data blocks and the parity data thereof in different physical disks, respectively.

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