High availability access to input/output devices in a distributed system

Claim 2

In a processing system including at least first and second processor nodes and an input/output device interconnected by a network for communication therebetween, the input/output device being actively controlled by driver software maintained by the first processor node, a method of switching active control of the input/output device from the first nodes to the second processor node, including the steps of: maintaining in the second processor node additional driver software for active control of the input/output device; maintaining a device ownership information for the input/output device that identifies the first processor node as having active control of the input/output device; detecting failure of the first processor node; and changing the device ownership information for the input/output device to identify the second processor node as having active control of the input/output device.

Claim 3

The method of claim 1, including the step of accessing the input/output device through the first processor node using the driver software or, if failure of the first processor node is detected, accessing the input/output device through the second processor node using the additional software.

Claim 4

The method of claim 1, wherein the step of maintaining the device ownership information includes the step of maintaining the device ownership information in each of the first and second processor nodes.

Claim 5

An article of manufacture comprising a number of processor nodes and at least one input/output device accessible by the number of processor nodes, at least first and second ones of the number of processor nodes including a memory wherein is located a driver computer program and a backup driver computer program, respectively, for active control of the input/output device, each of the number of processor nodes having memory containing an application computer program causing the number of processor units to implement the steps of: maintaining device ownership information for the input/output device that identifies the first processor node as having active control of the input/output device; using the driver computer program and the first one of the processing nodes to use the input/output device; detecting failure of the first processor node; changing the device ownership information for the input/output device to identify the second processor node as having active control of the input/output device; and thereafter, using the backup driver computer program and second one of the number of processor nodes to use the input/output device.

Claim 6

An article of manufacture comprising a number of processor nodes and at least one input/output device accessible by the number of processor nodes, at least first and second ones of the number of processor nodes including a memory wherein is located a driver computer program and a backup driver computer program, respectively, for active control of the input/output device, each of the number of processor nodes having memory containing an application computer program causing the number of processor units to implement the steps of: maintaining device ownership information for the input/output device that identifies the first processor node as having active control of the input/output device; using the driver computer program and the first one of the processing nodes to use the input/output device; detecting failure of the first processor node; changing the device ownership information for the input/output device to identify the second processor node as having active control of the input/output device; and thereafter, using the backup driver computer program and second one of the number of processor nodes to use the input/output device.

Claim 7

In a computer system that includes a plurality of processors, including a first and a second processor, the processors being interconnected by a communication network with a number of input/output devices, including a first input/output device, a method of fault tolerant control of the first input/output device that includes the steps of: maintaining active control of the first input/output device through driver software on the first processor; identifying to the plurality of processors the first processor as having active control of the first input/output device; maintaining backup driver software for controlling the first input/output device on the second processor; the plurality of processors using the first input/output device through the driver software on the first processor; detecting a fault of the first processor to identify to the plurality of processors the backup driver software as having active control of the first input/output device; thereafter, the plurality of processors using the first input/output device through the backup driver software on the second processor.

Claim 8

In a computer system that includes a plurality of processors, including a first and a second processor, the processors being interconnected by a communication network with a number of input/output devices, including a first input/output device, a method of fault tolerant control of the first input/output device that includes the steps of: maintaining active control of the first input/output device through driver software on the first processor; identifying to the plurality of processors the first processor as having active control of the first input/output device; maintaining backup driver software for controlling the first input/output device on the second processor; the plurality of processors using the first input/output device through the driver software on the first processor; detecting a fault of the first processor to identify to the plurality of processors the backup driver software as having active control of the first input/output device; thereafter, the plurality of processors using the first input/output device through the backup driver software on the second processor.

Claim 9

The method of claim 5, including the step of maintaining on a selected one of the plurality of processors a list respectively identifying the first and second once the plurality of processors as having the driver and backup driver software.

Claim 10

The method of claim 6 including the step of the plurality of processors wishing to use the first input/output device receiving first from the selected one of the plurality of processors an identification of the first processor on which the driver software is maintained, and thereafter using the first input/output device through the first processor.

Claim 11

The method of claim 5, including the step of maintaining on a selected one of the plurality of processors a list identifying the first processor as maintaining driver software and the second processor as maintaining the backup driver software; the detecting step including the steps of deleting the identification of the first processor from the list and adding the identification of the second processor as having backup driver software for active control of the first input/output device.

Claim 12

The method of claim 8, including the step of the plurality of processors wishing to use the input/output device first receiving from the selected one of the plurality of processors an identification of the first processor on which the driver software is maintained, and thereafter using the input/output device through the first processor.

Claim 13

The method of claim 9, the detecting step including sending to the plurality of processors that have used the input/output device the identification of the second processor, and thereafter such plurality of processors using the input/output device through the second processor.

Claim 16

The method of claim 11, including a preselected one of the processor operating to maintain a list identifying the first and second processors.

Claim 17

The method of claim 11, including a preselected one of the processor operating to maintain a list identifying the first and second processors, and wherein the detecting step includes the step of the preselected one of the plurality of processors sending to the plurality of processors that used the input/output device through the driver software and the first processor the identification of the second processor having the backup driver software.