Abstract: A method, apparatus and program product for detecting a communication event in a distributed parallel data processing system in which a message is sent from an origin to a target. A low-level application programming interface (LAPI) is provided which has an operation for associating a counter with a communication event to be detected. The LAPI increments the counter upon the occurrence of the communication event. The number in the counter is monitored, and when the number increases, the event is detected. A completion counter in the origin is associated with the completion of a message being sent from the origin to the target. When the message is completed, LAPI increments the completion counter such that monitoring the completion counter detects the completion of the message. The completion counter may be used to insure that a first message has been sent from the origin to the target and completed before a second message is sent.

Abstract: A parallel distributed computing system having a plurality of processors connected in a network of nodes, each node having software installed thereon, and a control workstation controlling the nodes in the network. A list of the levels of the software installed at each node is stored at the control workstation. A list of software subsystems affected by a command to be executed is stored at the nodes of the network, including the control workstation. In addition, a control script for each of said software subsystems is stored at the nodes, including the control workstation. Each control script provides a routine to be followed for the associated subsystem on the associated node or control workstation during the execution of the command. Since the control scripts are compatible with the level of software installed on the target node, the command will be performed such as to be compatible with the software installed on the target node.

Abstract: A barrier synchronization system in a distributed computing environment. A group of members, including a plurality of related processes executing on one or more processors of the distributed computing environment, is provided a protocol having a dynamic number of synchronization phases. The protocol is voted on by one or more members of the group to determine how the protocol should proceed for the group of members. The protocol may complete successfully, continue to another synchronization phase or be rejected. The group of members determines how many synchronization phases the protocol is to include.

Abstract: A method, apparatus and program product for message communication in a distributed parallel data processing system. A user message is sent from a sender to a receiver. The user message contains user data and a pointer to a header handler routine. The header handler routine includes a first pointer to a target user buffer and a second pointer to a completion routine. When the user message is received, a low level application program interface (LAPI) is informed which invokes the header handler routines which returns the first and second pointers. LAPI then transfers the user data to the user buffer indicated by the header handler routine, and invokes the completion routine indicated by the header handler routine to complete the transfer of the user message to the receiver.

Abstract: A system, method and program product for freeing tape drives so that long running jobs on a computer can be paused when other applications need the drives and restarted when the drives are available again. This is accomplished by pausing and resuming applications running on a computer including accessing a tape drive, on which is mounted a first tape, by a first application running on the computer, the accessing being through a pause/resume handler; pausing the first application responsive to an operator intervention to the pause/resume handler; storing parameters in the computer including location parameters indicating where the tape drive paused; mounting a second tape on the tape drive; and accessing the tape drive by a second application running on the computer. After the second application has completed access to the tape drive, the second tape is removed from the tape drive, and the first tape is remounted.

Abstract: An application programming interface that unifies a plurality of mechanisms into a single framework. The interface includes a mechanism for communicating between members of a process group of related processes, and a mechanism for synchronizing the related processes of the process group. Additionally, the application programming interface may include mechanisms for managing membership of the process group or a processor group of processors, and/or a mechanism for controlling a group state value for the process group.

Abstract: Actions responsive to changes in the state of independent process groups whose process members are spread across a group of nodes in a distributed computing environment. The process groups are arranged in a hierarchy having source process groups and target process groups immediately above and dependent upon the source process groups. A change in the state or membership of a process group will result in a group services function of the nodes in the group injecting the change into the source group members of the affected group. When the action is successfully completed, the change is reflected up the hierarchy to the target group member or members. Upon successful action by the target group, the target group becomes the new source group which in turn may have target groups, and the changes are again reflected up the hierarchy to the new target groups.

Abstract: A modular node assembly for a rack mounted multiprocessor computer in which the node assembly has a logic chassis and a removable chassis. The logic chassis contains logic cards including memory cards, a service processor card, Central Processing Unit (CPU) processor cards, and Input/Output (I/O) cards to which I/O and processor interconnecting cables are attached. The removable chassis contains the power supply module for the node, a node supervisor card, disk drives and cooling fans. The removable chassis is removable from the logic chassis without moving or disturbing the logic chassis. One fan of a pair of cooling fans in the removable chassis draws air through the power supply, which has relatively higher cooling needs, and blows the air into the logic chassis over logic modules having relatively lower cooling needs.

Abstract: A constant impedance air baffle assembly having two spaced apart generally parallel plates, each having a plurality of through holes for placing in line with a plurality of circuit cards to be cooled. The circuit cards are mounted on one side of a printed circuit board, and arranged in varying numbers and placements, depending on the number of cards desired. The air baffles provide a constant impedance to the air flow over the cards such that air does not bypass other components that need to be cooled when the circuit cards are removed. Further, the baffle plates include hanger tabs which may be hung over the edge of a printed circuit board to hold the parallel plates in place. The hanger tabs further include spacing slots for holding a pair of side-by-side printed circuit boards apart such that the printed circuit boards upon which said air baffle is hung cannot flex and short the pins on the backs thereof together.

Abstract: A barrier synchronization program product in a distributed computing environment. A group of members, including a plurality of related processes executing on one or more processors of the distributed computing environment, is provided a protocol having a dynamic number of synchronization phases. The protocol is voted on by one or more members of the group to determine how the protocol should proceed for the group of members. The protocol may complete successfully, continue to another synchronization phase or be rejected. The group of members determines how many synchronization phases the protocol is to include.

Abstract: An apparatus for synchronizing operator commands with a failover process in a distributed system having a control workstation and a plurality of nodes. One of the nodes of the distributed system is designated a primary node and one of the nodes is designated a backup node. The backup node includes a backup daemon for performing a failover process if the primary node fails such that the backup node becomes the primary node. Shell scripts send a command string to be synchronized with the operation of the backup daemon from the control workstation to the backup node. The backup daemon is then checked to determine if the backup daemon is sleeping, and, in the event the backup daemon is sleeping, commands derived from the command string are enqueued in a work queue for processing by the backup daemon. The backup daemon is then awakened such that the derived commands in the work queue are processed.

Abstract: An apparatus for a distributed system having a plurality of nodes and a switch network for passing messages between nodes, each message being sent from a source node to a target node. Each node is connected to the switch network by an adapter having a count register for adding the value of the packets in messages received by the adapter to the value in the count register and a threshold register for containing a desired threshold value. An interrupt generator generates interrupts when the value in the count register is equal to or greater than the value in the threshold register. The value in the threshold register may be changed under program control to enable or disable interrupts.

Abstract: Actions responsive to changes in the state of independent process groups whose process members are spread across a group of nodes in a distributed computing environment. The process groups are arranged in a hierarchy having source process groups and target process groups immediately above and dependent upon the source process groups. A change in the state or membership of a process group will result in a group services function of the nodes in the group injecting the change into the source group members of the affected group. When the action is successfully completed, the change is reflected up the hierarchy to the target group member or members. Upon successful action by the target group, the target group becomes the new source group which in turn may have target groups, and the changes are again reflected up the hierarchy to the new target groups.

Abstract: An abrasion control apparatus allowing a drawer member of an electronic enclosure to be inserted into a receptacle wherein the contacting sides of the drawer member and receptacle are made of aluminized steel. The invention includes a double thick side of the receptacle; the side of the receptacle which comes in contact with the side of the drawer member having a window in which is placed a plastic wear strip. The abrasion control apparatus further includes wear strips in a notched portion of the side of the receptacle and a bottom of the receptacle such that contact is prevented between the drawer and the metal sides of the receptacle as the drawer member is inserted into the receptacle.

Abstract: Actions responsive to changes in the state of independent process groups whose process members are spread across a group of nodes in a distributed computing environment. The process groups are arranged in a hierarchy having source process groups and target process groups immediately above and dependent upon the source process groups. A change in the state or membership of a process group will result in a group services function of the nodes in the group injecting the change into the source group members of the affected group. When the action is successfully completed, the change is reflected up the hierarchy to the target group member or members. Upon successful action by the target group, the target group becomes the new source group which in turn may have target groups, and the changes are again reflected up the hierarchy to the new target groups.

Abstract: A method of performing a software operation on a target of one of more processors in a distributed processing system wherein another processor is designated as a server. The method includes running a configuration program on the server to condition the server to serve on the target, the software operation which includes resource creation and object definitions; testing entry conditions in the configuration program for determining if entry conditions are met to serve the software operation on the target; if the entry conditions are met, serving the software operation on the target; at the completion of the software operation, testing exit conditions in the configuration program for determining if the software operation on the target completed successfully; if the exit conditions are met, exiting the software operation; returning to the configuration program to serve a second software operation on the target; and repeating until all software operations are served on the target.

Abstract: A method for use in a parallel distributed computing system having a plurality of processors connected in a network of nodes, each node having software installed thereon, and a control workstation controlling the nodes in the network. A list of the levels of the software installed at each node is stored at the control workstation. A list of software subsystems affected by a command to be executed is stored at the nodes of the network, including the control workstation. In addition, a control script for each of said software subsystems is stored at the nodes, including the control workstation. Each control script provides a routine to be followed for the associated subsystem on the associated node or control workstation during the execution of the command. Since the control scripts are compatible with the level of software installed on the target node, the command will be performed such as to be compatible with the software installed on the target node.

Abstract: Detecting the failure of the name server node and consulting a membership list of nodes in the domain to determine the crown prince (CP) node who is next in line to become the name server. The other available nodes in the domain periodically send recover messages to the CP node, and responsive to receiving the recover messages from all the other available nodes in the domain, the CP node perform a two phase takeover whereby the CP node becomes the name server for managing said processors in the domain. After the CP node becomes the name server, the other available nodes in the domain send data to the new name server necessary for the name server to manage the other available nodes in the domain. All request messages requesting management by the name server are stored locally until after the CP becomes the name server. The locally stored request messages are then processed by the other available nodes such that no request messages are lost during recovery.

Abstract: A system, method and program product for controlling multiple appearances of data on a display. A Controller is provided for receiving user instructions for data to be displayed, and for generating model management and view management instructions for controlling the appearance of data to be displayed. A Model is connected to the Controller for receiving model management instructions from the Controller, and for keeping track of changes to the appearance of data to be displayed. A ViewProxy is connected to said controller for receiving view management instructions, and connected to said Model for receiving model change notifications responsive to changes in the appearance of data to be displayed. Multiple Views are connected to the ViewProxy for receiving model change notifications. The ViewProxy determines to which Views the model change notifications are to be sent, and sends model change information to only those Views affected by said model changes.

Abstract: Managing membership of a domain of processors in a distributed computing environment including determining the lowest numbered node available in the domain and periodically sending grovel messages from the other available nodes to the lowest numbered node in the domain. Responsive to receiving all of the grovel messages by the lowest numbered node, the lowest numbered node performs a two phase commit whereby the lowest numbered node becomes a name server for managing the processors in the domain. The two phase commit includes sending an insert phase 1 (P1) message to the other available nodes from the lowest numbered node and, responsive to the insert P1 message, sending an acknowledge (ACK) message from the other available nodes to the lowest numbered node. Responsive to the ACK messages, a commit message is sent to the other available nodes notifying them that the lowest numbered node has become the name server.