Abstract: Input/output (I/O) measurement facilities are provided. An extended I/O measurement block facility is provided that enables measurement blocks to be stored in discontiguous areas of main storage and to be accessed directly via addresses. In a further aspect, an extended I/O measurement word facility is provided that facilitates the obtaining of measurement data for single I/O operations.

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 operating system is provided with access to a plurality of input/output subsystem images of the input/output subsystem. One or more controls are provided to the operating system image to enable the operating system image to access the plurality of input/output subsystem images.

Abstract: I/O measurement data for channels attached to logical control unit queues is obtained related to a plurality of logical control unit queues. A store secondary queue measurement data instruction specifies a range of queues for which extended secondary measurement blocks derived from the I/O measurement data are stored at a memory address specified by the store secondary queue measurement data instruction.

Abstract: I/O measurement data associated with the performance of an I/O operation process is gathered during the I/O process. The I/O measurement data is saved in an IRB memory location specified by a test subchannel instruction. An I/O interrupt signals the completion of the I/O operation process.

Abstract: Input/output (I/O) communications subadapters, such as subchannels, of an I/O subsystem are dedicated to components, such as I/O devices, of the I/O subsystem. The subadapters provide information about the associated components, in response to the execution of I/O instructions. To enhance I/O connectivity, a plurality of sets of I/O subadapters is provided to an operating system image. This allows programs of the operating system image to access a same component via different sets of I/O communications subadapters. Further, it enables an operating system image to use more than 64k subchannels.

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 operating system is provided with access to a plurality of input/output subsystem images of the input/output subsystem. One or more controls are provided to the operating system image to enable the operating system image to access the plurality of input/output subsystem images.

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. One or more input/output subsystem images of the plurality of input/output subsystem images are managed. An aspect of this management includes managing an input/output (I/O) configuration of an input/output subsystem image. This management may be performed dynamically.

Abstract: Input/output (I/O) measurement facilities are provided. An extended I/O measurement block facility is provided that enables measurement blocks to be stored in discontiguous areas of main storage and to be accessed directly via addresses. In a further aspect, an extended I/O measurement word facility is provided that facilitates the obtaining of measurement data for single I/O operations.

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. In response to an operating system image submitting an input/output (I/O) request requesting access to an input/output subsystem image, a determination is made as to whether the operating system image is authorized to access the input/output subsystem image. In response to the access being authorized, the I/O request is authorized.

Abstract: An input/output subsystem of a computing environment 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 includes one or more communications adapters used for communicating within the computing environment. A communications adapter is identified by hardware of the computing environment by using a first identifier, and it is identified by a program of the computing environment by using a second identifier. The identifiers can be of different sizes.

Abstract: Input/output interruptions are managed in computing environments that do not use dedicated per-guest interruption hardware to present interruptions. Dispatchable guest programs in the environment receive I/O interruptions directly without hypervisor intervention. This is facilitated by using one or more interruption controls stored in memory and associated with each guest program. For those guest programs that are not currently dispatchable, interruptions can be posted for the guests and notifications to the hypervisor can be aggregated. The hypervisor can then process a plurality of notifications for the plurality of guests in a single invocation.

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: The present invention provides a method for managing transmissions to a remote node having a buffer memory for receiving the transmitted packets and means for acknowledging the receipt of the packets. The method provides for a sender to maintain a sense of the availability of buffer memory even when acknowledging messages are lost with minimal impact on performance.