Abstract: An input/output subsystem is configured as a plurality of input/output subsystem images, each of which appears to a program as an independent input/output subsystem. An input/output subsystem image is identified by an input/output subsystem image identifier, which is used by various programs to designate the particular input/output subsystem image for which an I/O operation is to be performed. An input/output subsystem image includes, for instance, one or more input/output paths. An input/output path of an input/output subsystem image is identified by an input/output path identifier, as well as a physical input/output path identifier.

Abstract: An input/output subsystem is configured as a plurality of input/output subsystem images, each of which appears to a program as an independent input/output subsystem. An input/output subsystem image is identified by an input/output subsystem image identifier, which is used by various programs to designate the particular input/output subsystem image for which an I/O operation is to be performed. An input/output subsystem image includes, for instance, one or more input/output paths. An input/output path of an input/output subsystem image is identified by an input/output path identifier, as well as a physical input/output path identifier.

Abstract: An input/output subsystem is configured as a plurality of input/output subsystem images, each of which appears to a program as an independent input/output subsystem. An input/output subsystem image is identified by an input/output subsystem image identifier, which is used by various programs to designate the particular input/output subsystem image for which an I/O operation is to be performed. An input/output subsystem image includes, for instance, one or more input/output paths. An input/output path of an input/output subsystem image is identified by an input/output path identifier, as well as a physical input/output path identifier.

Abstract: A communications adapter is shared by a plurality of input/output (I/O) subsystem images of an I/O subsystem of a central processing complex. To enable the sharing, the communications adapter is configured to a plurality of I/O paths of the plurality of I/O subsystem images. An I/O subsystem may have one or more shared communications adapters.

Abstract: The utilization of various individual components of a channel is determined in order to learn which portion of a channel is busy and to what extent that portion is busy. The determination of a component's utilization is dependent on the type of component, as well as the operational characteristics of that component.

Abstract: A communications adapter is shared by a plurality of input/output (I/O) subsystem images of an I/O subsystem of a central processing complex. To enable the sharing, the communications adapter is configured to a plurality of I/O paths of the plurality of I/O subsystem images. An I/O subsystem may have one or more shared communications adapters.

Abstract: An input/output subsystem is configured as a plurality of input/output subsystem images, each of which appears to a program as an independent input/output subsystem. An input/output subsystem image is identified by an input/output subsystem image identifier, which is used by various programs to designate the particular input/output subsystem image for which an I/O operation is to be performed. An input/output subsystem image includes, for instance, one or more input/output paths. An input/output path of an input/output subsystem image is identified by an input/output path identifier, as well as a physical input/output path identifier.

Abstract: Asynchronous requests, such as input/output (I/O) requests, within a coprocessor of a computing environment are managed. The management of the asynchronous requests is based on priorities associated with the asynchronous requests. This management includes, for instance, selecting an asynchronous request to be processed using a priority scheme, and/or affording resources to the asynchronous requests using a priority scheme.

Abstract: Asynchronous requests, such as input/output (I/O) requests, within a coprocessor of a computing environment are managed. The management of the asynchronous requests is based on priorities associated with the asynchronous requests. This management includes, for instance, selecting an asynchronous request to be processed using a priority scheme, and/or affording resources to the asynchronous requests using a priority scheme.

Abstract: A method of providing direct data processing access in a network computing system environment. The system environment has a main storage which can be connected to one or more application servers and is in processing communication with an interface element. The interface element has at least one adapter and can be connected to one or more application user(s). One or more queues are established in the main storage that can handle data without causing interrupts in the running programs. Incoming data is received using the adapter and as data is received or modified, the status of the network computing system will be updated to reflect the new data or change. Data is then processed in the main storage after interrogating the multiple existing queues in the main storage and forwarding them in turn to their appropriate destination or application server after a determination has been made by interrogating these queues.

Abstract: A queuing method and apparatus for transfer or incoming and outgoing data in a network environment having a main storage is presented. A plurality of queue sets are provided in the main storage with at least one or more sets being dedicated for input and output. The queues can share access to a plurality of devices in the network across a plurality of communication stacks. Various network resources are mapped to the queues in order to facilitate resource allocation and dynamic configuration by providing initialization of a plurality of configuration parameters. In this way dynamic expanding and contracting of the number of queues in each set as dictated by traffic patterns and feedback indicators is provided.

Abstract: Execution of input/output operations is controlled by one or more suspend and/or resume mechanisms. Suspension of an input/output operation is accomplished by one of a number of mechanisms including, for instance, a START SUBCHANNEL instruction with execution limits, a SUSPEND SUBCHANNEL instruction with or without a suspension time limit, or a suspend subchannel channel command word with or without a suspension time limit. Subsequent to suspending execution of a channel program, execution can be resumed automatically or by issuing a RESUME SUBCHANNEL instruction with limits or a resume subchannel channel command word with limits.

Abstract: Coupling execution of channel programs without central processing unit supervision controls data transfer between input/output devices through a main storage of a data processing system. In one embodiment, channel programs to be coupled are generated by a program running on a data processing system central processing unit. The channel program on the input subchannel includes channel commands referencing the output subchannel and operating to cause resumption of the output subchannel. The channel program on the output subchannel includes suspend channel commands directed to itself which correspond to the resume channel commands in the channel program on the input subchannel. In alternative embodiments values in channel commands can change values in, or reference, control blocks to effect execution of other channel programs.

Abstract: Disclosed is a data processing system for presenting concurrent requests for access to peripheral devices up to the number of subchannels available for handling input/output operations. A computer system provides a plurality of subchannels and affiliated unit control blocks for input/output operations between main storage and the peripheral devices. The unit control blocks comprise two groups, including a first dedicated to the peripheral devices and a second group available for dynamic association with the peripheral devices on a demand basis. The unit control blocks are termed base unit control blocks and alias unit control blocks, respectively. Upon system initialization, alias unit control blocks for a given logical subsystem are linked in a free pool. To initiate an input/output operation a program executing on the CPU first queries a base unit control block for a target peripheral device to determine its availability.

Abstract: A data processing I/O system including a main storage for storing data and data processing instructions arranged in software programs, and a channel subsystem having hardware for reporting conditions in the channel subsystem to the software. A special Channel Subsystem Call (CHSC) instruction is used to store event information from the channel subsystem into the main memory for use by the software such that new or restored resources such as a channel path, a channel path and partial control unit link address, or a channel path and full control unit link address, may be originally made accessible, or may be restored to the I/O system. A mechanism is also provided to inquire of a device how long it expects to not be accessible to give the device sufficient time to reset itself before it is varied offline, thus preventing a device from being isolated or "boxed" prematurely.

Abstract: Control unit level reset operations in systems having switched point-to-point I/O interface topologies is accomplished by determining and storing channel path identification numbers (CHPID's) and control unit link addresses (CULA's) for each device in the system, scanning this stored data to find devices whose CHPID's and CULA's match the CHPID and CULA for a device or a control unit having a reported error, quiescing devices with such matching CHPID's and CULA's, issuing a control unit level reset command and reactivating the quiesced devices. For systems having both multidropped and switched point-to-point topologies, provision is made for preliminarily determining whether a given control unit reset can be performed on the control unit level.

Abstract: Provides a method for increasing the connectivity of I/O resources to a multiplicity of operating systems (OSs) running in different resource partitions of a computer electronic complex (CEC) to obtain sharing of the I/O resources among the OSs of the CEC, including channels, subchannels (devices), and control units (CUs). The invention provides image identifiers (IIDs) for assigning resources to the different OSs. Each shared I/O resource has a sharing set of control blocks (CBs) in which a respective CB is assigned to (and located by) a respective IID of one of the OSs. Each of the CBs in a sharing set provides a different image of the same I/O resource. The different CB images are independently set to different states by I/O operations for the different OSs, so that the OSs can independently share the same I/O resource.

Abstract: In a multi-system complex having central processing complexes (CPCs) and subsystems, a hardware facility for prompt interdicting I/O and message operations. A CPC or subsystem failure causes as interruption in the availability of the data bases to the attached network of terminals. Often such networks have thousands of terminals. Even a short loss of data is detrimental. Therefore the CPC or subsystem takeover must be accomplished as quickly as possible and the I/O attached to the failing CPC or subsystem must be interdicting to release it for use to the rest of the complex. The disclosed hardware facility provides a mechanism which is program initiated and controlled and which guarantees the prompt completion of the interdiction function.

Abstract: An I/O request time limit value is set in a request-based, device-based, data-set-based, or workload-based time limit field, for transactions performing I/O operations to I/O devices in a data processing system. A scan routine compares the total time for the I/O request (including waiting time and retry time) against the appropriate time limit(s), and terminates the I/O request if the time limit is exceeded. If an active I/O request is interrupted as a result of an I/O error, retry is prohibited if the total I/O request time (including retry time) exceeds the appropriate time limit, or is within a threshold value of the appropriate time limit.

Abstract: A method for acquiring the node identifier of a node in a data processing input/output (I/O) system having a plurality of nodes. This procedure is part of the initialization of each node in the I/O system and may be used to establish the configuration of the I/O system such that if a connection breaks or a fault occurs between nodes, the configuration can be confirmed after the break or fault is corrected. This prevents data from being sent to the wrong device if lines were connected in a different configuration during the correction of a fault. The node identifier is a worldwide-unique identifier such that only one node is identified by a node identifier. The node identifier contains a validity code that specifies if the node identifier is valid. Also disclosed is a retry procedure for retrying the acquisition of a node identifier if the acquired node identifier is not valid, and a deferral procedure which defers the retry procedure if a link is not available.