Failure resistant multiple computer system and method
First Claim
1. A failure resistant method of operating a plurality of computers each with their corresponding independent local memory, each substantially simultaneously operating a corresponding portion of an application program written to execute on only a single computer, and each being connected via a communications network to permit updating of corresponding memory locations, said method comprising the steps of:
- (i) categorizing the memory locations of said local memories into a first reachability category in which the local memory locations are replicated in selected ones, or all, of said computers and therefore require updating via said communications network with changes to corresponding memory locations of the other computers to maintain substantial memory coherence, and into a second category in which the local memory locations are present only in the local computer and therefore no updating is required, (ii) detecting failure of any one of said multiple computers, and (iii) modifying said first category to remove therefrom, if present, any reference to the failed computer, whereby no attempt is made to update any first category locations of said failed computer.
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Accused Products
Abstract
The updating of only some memory locations in a multiple computer environment in which at least one applications program (50) executes simultaneously on a plurality of computers M1, M2 . . . Mn each of which has a local memory, is disclosed. Memory locations (A, B, D, E, X) in said local memory are categorized into two groups. The first group of memory locations (X1, X2, . . . Xn, A1, A2, . . . An) are each present in other computers. The second group of memory locations (B, E) are each present only in the computer having the local memory including the memory location. Changes to the contents of memory locations in the first group only are transmitted to all other computers. A computer failure detection mechanism is disclosed to prevent updating of any first group memory locations of any failed computer.
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Citations
15 Claims
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1. A failure resistant method of operating a plurality of computers each with their corresponding independent local memory, each substantially simultaneously operating a corresponding portion of an application program written to execute on only a single computer, and each being connected via a communications network to permit updating of corresponding memory locations, said method comprising the steps of:
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(i) categorizing the memory locations of said local memories into a first reachability category in which the local memory locations are replicated in selected ones, or all, of said computers and therefore require updating via said communications network with changes to corresponding memory locations of the other computers to maintain substantial memory coherence, and into a second category in which the local memory locations are present only in the local computer and therefore no updating is required, (ii) detecting failure of any one of said multiple computers, and (iii) modifying said first category to remove therefrom, if present, any reference to the failed computer, whereby no attempt is made to update any first category locations of said failed computer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 15)
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- 9. A failure resistant multiple computer system in which a plurality of computers each has a corresponding independent local memory, each simultaneously operates a corresponding portion of an application program written to be executed only on a single computer, and each is connected via a communications network to permit updating of corresponding memory locations, said system including a reachability means to categorize memory locations of said local memories into a first category in which the local memory locations are replicated in selected ones, or all, of said computers and therefore require updating via said communications network with changes to corresponding memory locations of other computers, to maintain substantial memory coherence, and into a second category in which the local memory locations are present only in the local computer and therefore no updating is required, and wherein said system further includes a failure detection means connected to each said computer to detect failure of any one of said multiple computers, and a reachability modifier connected to said failure connection means and to said reachability means to modify said reachability means by modifying said first category to remove therefrom, if present, any reference by the failed computer whereby no attempt is made to update any first category memory locations of said failed computer.
Specification