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CPU implemented method for backing up modified data sets in non-volatile store for recovery in the event of CPU failure

  • US 5,454,099 A
  • Filed: 07/25/1989
  • Issued: 09/26/1995
  • Est. Priority Date: 07/25/1989
  • Status: Expired due to Fees
First Claim
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1. In a central processing unit (CPU) having a non-volatile store containing groups of logically independent non-fragmented, non-dispersed sequential datasets, and processor means,said processor means including means for updating and for backing up datasets in each group , said backing up occurring by copying said datasets into a first failure independent part of the nonvolatile store on a selective and on a periodic basis,said processor means further including timing means for assigning a maximum time interval (GBF) to each group in said store and for amending each dataset in each group with a date time stamp denoting dates and times of last backup and last update,a CPU implemented method for backing up of non-fragmented, non-dispersed sequential datasets in non-volatile store and for the recovery thereof in the event of CPU failure, comprising the steps of:

  • (a) during a backup cycle, ascertaining those data sets in each group conforming to at least one of the following criteria;

    (1) the date of their last update lies between an instant date and the date of last backup AND the difference between the instant date and the date of last backup equals or exceeds a first predetermined minimum backup interval (MBF), or(2) the difference between the instant date and the date of last backup exceeds GBF, AND MBF equals or is less than GBF;

    (b) copying the ascertained data sets to said first failure independent part of said non-volatile store; and

    (c) during a recovery cycle, recopying into a second failure independent part of non-volatile store from the first part of non-volatile store said backed up datasets and groups.

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