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Fault tolerant data processing system

  • US 5,325,517 A
  • Filed: 05/17/1989
  • Issued: 06/28/1994
  • Est. Priority Date: 05/17/1989
  • Status: Expired due to Fees
First Claim
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1. In a fault tolerant data processing system of the type in which a first plurality of processing units greater than two concurrently perform identical operations under program control, each processor unit being coupled to hardware including fault tolerant I/O devices and storage, in which the processor states are periodically compared for determining the presence of an error in the processor units, and in which fault tolerant operations are continued so long as two of the units whose states can be compared are error free, in combination therewithan additional plurality of processing units, one for each processing unit in the first plurality, having an architecture different than that of said first plurality of units, said additional units performing identical operations concurrently with each other under program control,means periodically comparing the states of the additional plurality of units to detect errors in the additional plurality of units.means including an application program executing on said first plurality of units for uncoupling each unit in the first plurality from its respective hardware, and coupling each unit in the first plurality to a respective unit in the additional plurality,means controlled by said first plurality of units while uncoupled from its respective hardware, and by said application program, for passing I/O commands and data directly from the additional plurality of units to respective units in the first plurality,means controlled by said first plurality of units and the application program for converting said commands and data to commands executable by and data useable by said first plurality of units to permit the first plurality of fault tolerant processing units to act as I/O controllers for the additional plurality of processing units, andmeans associated with said first plurality of processing units responsive to said periodic comparisons for removing one of the processing units in the additional plurality along with its respective processing units in the first plurality from service upon detection of an error in either the one of the processing units in the additional plurality or its respective unit in the first plurality, permitting continued fault tolerant operation of the other processing units in the first and respective additional pluralities of processing units so long as two units each of said first and respective additional pluralities of units are error free.

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