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Fault-tolerant computer system with auto-restart after power-fall

  • US 5,317,752 A
  • Filed: 11/16/1992
  • Issued: 05/31/1994
  • Est. Priority Date: 12/22/1989
  • Status: Expired due to Term
First Claim
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1. A method of operating a computer system having a central unit (CPU), memory including volatile memory and non-volatile memory, a main power supply, a backup power supply, and a plurality of devices peripheral to said CPU said method comprising the steps of:

  • (a) executing processes in the central processing unit (CPU) from memory, while the main power supply provides power to said computer system;

    (b) detecting a failure of said main power supply and, in response thereto, providing power to said computer system from the backup power supply and executing a shutdown procedure in said CPU, said shutdown procedure including first warning said processes of an impending shutdown of the computer system, said processes responding to said warning in a manner varying from process to process, and then copying state information of said computer system from said memory to said non-volatile storage, wherein said state information includes state information of the processes and state information of the devices;

    (c) after completing said shutdown procedure, if said power supply has been restored, automatically initiating a restart procedure;

    (d) said restart procedure including reading said stored state from said non-volatile storage and restarting said processes and continuing executing without rebooting;

    (e) or, if said power supply has not been restored within a predetermined period of time after completion of said shutdown procedure, automatically shutting down said backup power and ceasing execution by said CPU.

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