Systems and methods for split mode operation of fault-tolerant computer systems
First Claim
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1. A method for splitting a fault-tolerant computer system comprising at least two processing subsystems executing in lockstep, wherein each processing subsystem executes identical instructions substantially simultaneously, the method comprising:
- designating an active subsystem and an upgrade subsystem from among the at least two processing subsystems, the active subsystem comprising a first processor and the upgrade subsystem comprising a second processor;
isolating components within the upgrade subsystem from the other subsystems;
splitting the fault-tolerant computer system after designating the active subsystem and the upgrade subsystem such that, at the time of the split, the first processor of the active subsystem and the second processor of the upgrade subsystem have identical operational states, but thereafter operate independently for the duration of a software upgrade and cease lockstep operation during the software upgrade; and
after the software upgrade, resuming lockstep operation.
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Abstract
Methods and systems are provided by which a computer system, and in particular, a lockstep fault-tolerant computer system, may be split into a plurality of independently operational subsystems. Each subsystem may be examined, managed or upgraded by an administrator while the overall computer system continues to service end-users. Finally, the separate subsystems may be merged in an efficient fashion and fault-tolerant operation will resume upon the combined system.
52 Citations
37 Claims
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1. A method for splitting a fault-tolerant computer system comprising at least two processing subsystems executing in lockstep, wherein each processing subsystem executes identical instructions substantially simultaneously, the method comprising:
- designating an active subsystem and an upgrade subsystem from among the at least two processing subsystems, the active subsystem comprising a first processor and the upgrade subsystem comprising a second processor;
isolating components within the upgrade subsystem from the other subsystems;
splitting the fault-tolerant computer system after designating the active subsystem and the upgrade subsystem such that, at the time of the split, the first processor of the active subsystem and the second processor of the upgrade subsystem have identical operational states, but thereafter operate independently for the duration of a software upgrade and cease lockstep operation during the software upgrade; and
after the software upgrade, resuming lockstep operation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
- designating an active subsystem and an upgrade subsystem from among the at least two processing subsystems, the active subsystem comprising a first processor and the upgrade subsystem comprising a second processor;
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22. A computer system comprising at least two processing subsystems operating in lockstep, wherein each processing subsystem executes identical instructions substantially simultaneously, configured to perform the following steps:
- designate a first subsystem and an second subsystem from among the at least two processing subsystems, the first subsystem comprising a first processor and the second subsystem comprising a second processor;
isolate components within the second subsystem from the first subsystem; and
split the system after designating the first subsystem as active subsystem and the second subsystem as upgrade subsystem such that, at the time of the split, the first processor of the first subsystem and the second processor of the second subsystem have identical operational states, but thereafter operate independently for the duration of a software upgrade and cease lockstep operation during the software upgrade. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
- designate a first subsystem and an second subsystem from among the at least two processing subsystems, the first subsystem comprising a first processor and the second subsystem comprising a second processor;
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37. A dual-mode redundant, fault-tolerant computer system comprising:
- a first subsystem comprising a first processor, a first network connection, and a first local mass storage medium; and
a second subsystem comprising a second processor, a second network connection, and a second local mass storage medium, the second subsystem connected to and in lockstep operation with the first subsystem such that the first processor and second processor operate in lockstep, wherein each processing subsystem executes identical instructions substantially simultaneously;
wherein, the second subsystem may be split from the first subsystem after designating the first subsystem as active subsystem and the second subsystem as upgrade subsystem, and operate independently for the duration of a software upgrade without rebooting or physically removing either subsystem and wherein lockstep operation of the first processor and second processor ceases during the software upgrade.
- a first subsystem comprising a first processor, a first network connection, and a first local mass storage medium; and
Specification