I/O control apparatus having check recovery function
First Claim
1. An I/O control apparatus in a computer system which has one or more CPUs, a main memory, and one or more I/O devices and in which said CPUs periodically save the internal state of said CPUs and the contents of said main memory as a checkpoint, and the internal status of said CPUs and the contents of said main memory of a most recent checkpoint are restored when a fault occurs in said computer system to restart data processing comprising:
- I/O device state storing means for logging parameters of a state setup sequence of said I/O devices performed by said CPUs, said I/O device state storing means including means for erasing part of previously logged parameters of an I/O device which is made unnecessary when a new state of said I/O device is set; and
I/O device state restoring means for restoring the state of said I/O devices to that of the most recent checkpoint by first initializing said I/O devices and by second reexecuting the state setup sequence according to said logged parameters stored by said I/O device state storing means.
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Abstract
In a computer system, when a CPU performs a state setting operation, such as setting an appropriate operation mode for I/O devices, the log data of the state setting operation is stored in a log storage area. Upon occurrence of a fault in the computer system, the I/O devices are cleared, and the state setting operation of the I/O devices is performed on the basis of the log data of the prior state setting operation stored in the log storage area. Therefore, the states of the I/O devices can be recovered to a state at a checkpoint when the process is restarted.
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Citations
32 Claims
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1. An I/O control apparatus in a computer system which has one or more CPUs, a main memory, and one or more I/O devices and in which said CPUs periodically save the internal state of said CPUs and the contents of said main memory as a checkpoint, and the internal status of said CPUs and the contents of said main memory of a most recent checkpoint are restored when a fault occurs in said computer system to restart data processing comprising:
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I/O device state storing means for logging parameters of a state setup sequence of said I/O devices performed by said CPUs, said I/O device state storing means including means for erasing part of previously logged parameters of an I/O device which is made unnecessary when a new state of said I/O device is set; and I/O device state restoring means for restoring the state of said I/O devices to that of the most recent checkpoint by first initializing said I/O devices and by second reexecuting the state setup sequence according to said logged parameters stored by said I/O device state storing means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An I/O control apparatus in a computer system which has one or more CPUs, a main memory, and one or more I/O devices and in which said CPUs periodically save the internal state of said CPUs and the contents of said main memory as a checkpoint, and the internal state of said CPUs and the contents of said main memory of a most recent checkpoint are restored when a fault occurs in said computer system to restart data processing, comprising:
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I/O device state storing means for logging parameters of a state setup sequence of said I/O devices performed by said CPUs; and I/O device state restoring means for restoring the state of said I/O devices to that of the most recent checkpoint by first initializing said I/O devices and by second reexecuting the state setup sequence according to said logged parameters stored by said I/O device state storing means, said I/O device state restoring means including means for skipping initializing and reexecuting the state setup sequence of an I/O device in which a new state setup sequence has not been performed since the most recent checkpoint. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An I/O control apparatus in a computer system which has one or more CPUs, a main memory, and one or more I/O devices and in which said CPUs periodically save the internal state of said CPUs and the contents of said main memory as a checkpoint, and the internal state of said CPUs and the contents of said main memory of a most recent checkpoint are restored when a fault occurs in said computer system to restart data processing, comprising:
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I/O device state storing means for logging parameters of a state setup sequence of said I/O devices performed by said CPUs; I/O device state restoring means for restoring the state of said I/O devices to that of the most recent checkpoint by first initializing said 10 devices and by second reexecuting the state setup sequence according to said logged parameters stored by said I/O device state storing means; request block creating means for creating, when an application process in said computer system makes an I/O request, a request block in said main memory which contains information necessary to perform said I/O request; I/O execution processes for performing an I/O operation by executing I/O device driver routines according to a request block; and I/O execution processes initializing means for initializing, upon restart from the most recent checkpoint after a fault occurrence, said I/O execution processes other than in initial state and causing I/O operations being performed by said I/O execution processes to be reexecuted from the beginning. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29)
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30. An I/O control method in a computer system which has one or more CPUs, a main memory, and one or more I/O devices and in which said CPUs periodically save the internal state of said CPUs and the contents of said main memory as a checkpoint, and the internal state of said CPUs and the contents of said main memory of the most recent checkpoint are restored when a fault occurs in said computer system to restart data processing, comprising the steps of:
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logging parameters of a state setup sequence of said I/O devices performed by said CPUs, said logging step including erasing part of previously logged parameters of an I/O device which is made unnecessary when a new state of said I/O device is set; and restoring the state of said I/O devices to that of the most recent checkpoint by first initializing said I/O devices and by second reexecuting the state setup sequence according to said logged parameters.
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31. An I/O control method in a computer system which has one or more CPUs, a main memory, and one or more I/O devices and in which said CPUs periodically save the internal state of said CPUs and the contents of said main memory as a checkpoint, and the internal state of said CPUs and the contents of said main memory of a most recent checkpoint are restored when a fault occurs in said computer system to restart data processing, comprising the steps of:
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logging parameters of a state setup sequence of said I/O devices performed by said CPUs; and restoring the state of said I/O devices to that of the most recent checkpoint by first initializing said I/O devices and by second reexecuting the state setup sequence according to said logged parameters, said restoring step including initializing and reexecuting the state setup sequence of an I/O device in which a new state setup sequence has been performed since the most recent checkpoint.
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32. An I/O control method in a computer system which has one or more CPUs, a main memory, and one or more I/O devices and in which said CPUs periodically save the internal state of said CPUs and the contents of said main memory as a checkpoint, and the internal state of said CPUs and the contents of said main memory of a most recent checkpoint are restored when a fault occurs in said computer system to restart data processing, comprising the steps of:
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logging parameters of a state setup sequence of said I/O devices performed by said CPUs; restoring the state of said I/O devices to that of the most recent checkpoint by first initializing said I/O devices and by second reexecuting the state setup sequence according to said stored logged parameters; creating, when an application process in said computer system makes an I/O request, a request block in said main memory which contains information necessary to perform said I/O request; performing I/O operations, using I/O execution processes, by executing I/O device driver routines according to a request block; and initializing, upon restart from the most recent checkpoint after a fault occurrence, said I/O execution processes other than in initial state and causing I/O operations being performed by said I/O execution processes to be reexecuted from the beginning.
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Specification