International Business Machines Corporation

Peter Frank Corbett

Sandra Johnson Baylor

Mark Edwin Giampapa

Julian Satran

Blake G Fitch

Anthony Simon Bolmarcich

Dror Gershon Feitelson

Chan-ik Park

The invention is a system and method for establishing a communication connection between two programs, each running on multiple processors of a distributed or shared memory parallel computer, or on multiple computers in a cluster of workstations or a set of network connected workstations. The invention includes all protocols that require one of the two programs that wish to communicate to actively initiate the communication session, while the other program passively accepts such direct communication session initiations. No task of the active program of the connection will attempt to communicate with tasks of the passive program until after it has been notified that all passive program tasks are prepared to receive messages, and that all other active program tasks are prepare to receive messages from the passive programs tasks, and vice versa. Further, the tasks of the passive program are free running during establishment of the connection; while the active program tasks are free to run provided that they do not attempt to communicate with the second program. Another aspect of the invention provides a secondary indirect communication channel mediated by as resource manager separate from the active and passive programs.

System and method for establishing direct communication between parallel programs

A method for storing redundant information in an array of data storage devices such that data is protected against two simultaneous storage device failures. The method assigns each data block to two different parity sets, each protected by a different parity block. The protected data blocks and the parity block each reside on a different data storage device.

Efficient method for providing fault tolerance against double device

A protocol for achieving atomic multicast in a parallel or distributed computing environment. The protocol guarantees concurrency atomicity with a maximum of m-1 message passes among the m server nodes of the system. Under one embodiment of the protocol, an access component message is transferred to the server nodes storing data to be accessed. The first server node of the plurality generates a token to be passed among the accessed nodes. A node can not process its request until it receives the token. A node may pass the token immediately upon ensuring that it is the current expected token.

Parallel network communications protocol using token passing

A scheme is presented for storing data on disks in such a way that a checkpoint can easily be taken across several disks connected to different processors in a distributed or parallel computer. A checkpoint can be used to restore the entire disk system to a known state after one or more of the disks or processors fails. When a failure occurs, the disk system is restored to its state at the current checkpoint. The scheme allows significant saving in disk space by requiring that only the data modified since the last checkpoint be copied. The checkpointing algorithm is presented as part of the invention. The invention allows checkpointing of disk space independently of the use of the disk space, for example, in a file system.

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Scarsdale, NY, United States of America

Peter Frank Corbett