International Business Machines Corporation

Audrey A Helffrich

David Arlen Elko

Jeffrey Mark Nick

Michael D Swanson

Jeffrey Alan Frey

Brian B Moore

John F Isenberg, Jr

Dennis J Dahlen

Joseph A Williams

Thomas Anthony Gregg

Steven N Goss

Gottfried Andreas Goldrian

Richard Pervin King

Jimmy Paul Strickland

Wendell W Wilkinson

Stewart Laundon Palmer

David Harold Surman

Ambrose A Verdibello, Jr

Jeffery M Mick

Jeffery M Nick

Two or more user applications executing on one or more processors, each controlled by an operating system, share use of a list and subsidiary list structure within a Structured External Storage (SES) facility to which each processor is connected. One of the applications registers interest in particular state transitions affecting one or more subsidiary lists within the list structure, causing a process within the SES to notify the appropriate processor when a list operation causes the particular state transition, without interrupting processing on the processor. The application receives notice of the state transition by periodically polling a vector within the processor, or by receiving control when a test by the operating system of a summary indicator for the vector causes an application exit to be driven.

System and method for management of object transitions in an external

A method and apparatus for optimizing a data structure of an external data storage facility shared by a plurality of data processing systems, the data structure being allocated by a first allocation command which includes first allocation parameters based on an amount of storage space in the external data storage facility assigned for creation of the data structure and a composition of the data structure, includes a device for determining values of the first allocation parameters, to thereby determine a first composition of the data structure, a device for determining an actual usage of the data structure, to thereby determine a second composition of the data structure, a device for comparing the first composition of the data structure with the second composition of the data structure, and a device for issuing, based on an output from the comparing device, a second allocation command having second allocation parameters, to the data structure for reallocation thereof. The issuing device includes a device for adjusting the first composition of the data structure to the second composition, as storage space in the external data storage facility and processing cycles become available to execute the second allocation parameters. Until the second allocation parameters are achieved, the reallocation of the data structure remains pending and all processing commands are accepted and processed by the external data storage facility.

Method and apparatus for expansion, contraction, and reapportionment of

A Structured External Storage (SES) processor is linked by a communication means to one or more general purpose processors. Two or more applications executing on the one or more general purpose processors communicate function request messages to a message processor within the SES to effect serialized sharing of data within the SES. Within the message processor, a predicate function means executes unconditionally on receipt of one of the function request messages, and a data function means executes conditionally and atomically with respect to the predicate function means following a 'successful' condition produced by the predicate function means. The predicate function means comprises a predicate compare function means and a predicate update means, the predicate compare function means executing unconditionally and producing a 'successful' or 'unsuccessful' result, the predicate means executing conditionally and atomically with respect to the predicate compare function means, following a 'successful' result by the predicate update compare function means.

Method and apparatus for performing conditional operations on externally

Computer system processing complexes which can operate actually or apparently synchronously and in parallel or asynchronously in a network have a coupling facility for sending and receiving commands, responses, and data. The memory for the central processing complexes (which is accessible to each of the processing elements) is provided with storage for messages and data for coupling over a communication channel interface. Each of a plurality of processing elements (CPC) has data objects used to maintain state information for shared data in the coupling facility storage. The coupling facility can receive both message commands and data, sending data and responses to messages, and sending and receiving secondary messages. The processing element accessible memory provides a state information buffer control information operation memory block for describing the hardware communication environment associated with the computer system mechanism for storage of state information pertaining to a communications buffer residing in said coupling facility storage. The communication channel has a set of address registers. The system employs four new instructions, PREPARE CHANNEL BUFFER, SIGNAL CHANNEL BUFFER, MOVE CHANNEL BUFFER DATA, and TEST CHANNEL BUFFER, to enable a coupling facility control program to directly manipulate the address registers and control the flow of data, commands and responses between the coupling-facility storage and communication channels for the central processing elements. This provides a direct interface between the coupling facility and an intersystem communication channel for the receipt of messages and data and the related receiving functions.

Mechanism for receiving messages at a coupling facility

A computer system with a coupling facility is provided with a plurality of processors and a plurality of intersystem channels coupled to the processors via a memory bus. The coupling facility includes a memory bus interface for the memory bus and a plurality of channels for coupling said channels to said processors. The memory bus interface includes an adapter with at least two hardware vectors provided for command detection, command isolation, and parallel testing of the error states of the intersystem channels, one which detects a command vector arrival, and a second which contains error state vector indicators. A LOCATE CHANNEL BUFFER (LCB) instruction is employed which performs a sense and reset operation on the command vector to identify and isolate a new command, and subsequently reads a vector of said error states vector indicator to determine the presence or absence of link errors.

Multi channel inter-processor coupling facility processing received

A mechanism for communicating messages, each including a command and a response, in a network having central processing complexes (CPCs) and one or more coupling facilities. Each coupling facility has a central processor for executing instructions and a main storage. Messages are sent from a message control block in the main storage of the CPC sending the message, and the response to the message is received in a message response block of the CPC without an interrupt to the program being executed by the central processor of the CPC. Each message from a CPC to the coupling facility may include a command and an indicator bit which instructs the coupling facility to execute the command either in synchronism with or asynchronously to the execution of the sending processor. The coupling facility executes the command and returns a response which is received in a message response block of the main storage of the sending CPC without an interrupt to any program being executed by the central processor of that CPC.

In a multiprocessing system having a coupling facility, communicating

A message path mechanism in a network having central processing complexes (CPCs) joined by message paths to a coupling facility. The coupling facility locates message paths for sending messages from one CPC to another and for sending messages between the coupling facility and one or more of the CPCs. A message path status table is provided having an entry for each of the message paths. Each entry has an indicator indicating whether its message path is active or inactive. multiple connections between the coupling facility and systems in the CPCs are registered in the coupling facility. Also provided is a mechanism for validating that each message path is connected properly such that if a message path is disconnected and then reconnected to a CPC, the validation mechanism insures that the message path has been reconnected correctly.

Coupling facility for receiving commands from plurality of hosts for

One or more central processing complexes (CPC's), each with one or more programs being executed, issue commands to a structured electronic storage (SES). The commands include ones that create or delete data structures in SES, and attach or detach users to the data structures. The commands include a comparative authority value operand and a new authority value operand. A data structure or user control information has an associated existing authority value. If the comparative authority value matches the existing authority value, the existing authority value is replaced by the new authority value, and the command is executed. If there is a mismatch, the existing authority value is returned to the program that issued the command, and the command is not executed in SES. This enables software to serialize management of SES and maintain a consistent view of objects in SES in the presence of faulty CPC's, without causing correctly operating CPC's to experience errors or undue delays.

Authorization method for conditional command execution

A Structured External Storage (SES) Facility is coupled to one or more Central Electronic Complex (CEC) Processors, each linked to each other in a System Processing Complex (Sysplex). Applications within a CEC communicate with the SES via messages over a communication means. The SES comprises one or more List Structures, each structure comprising one or more Lists, each List comprising a list control and none or more List Entries. List Entries may be keyed or unkeyed, have a List Entry Identifiers (LEID), created within the SES, and unique within a particular List Structure. List Entries may also have a unique (within a List Structure) Name, created and managed by the application. A plurality of List commands are provided for creating, locating, moving and deleting List Entries--with location reference possible by LEID, Name, Key, Location within List, or a combination of Key and Location within Key. Name and LEID are preserved between moves, while Key may or may not be changed, and will be used to determine relative location.

Apparatus and method for list management in a coupled data processing

One or more Central Processing Complexes (CPC), each with one or more programs being executed, become command initiators by issuing commands requesting an action to be performed by a command responder. The responder is a Structured Electronic Storage (SES) which comprises a coupling facility. The SES receives commands to be executed over a plurality of links interconnecting the CPC's and SES, and returns a response to the program that issued the command. The SES is the focal point for the CPC's to share data, control locks, and manipulate lists or queues. This couples the autonomous CPC's into a System Complex (Sysplex) displaying a single system image. An indicator associated with each of the links is set by SES when it appears to a initiator that problems on the link exist. The set state of any indicator prevents SES from starting execution of any subsequent commands. This preserves the orderly, sequential execution of commands to insure consistent states of data in SES, and allows the program that issued the command to determine exactly how the command ended at SES. Data associated with execution of the command is stored in a status save area of SES for subsequent access by the program.

Command execution system for using first and second commands to reserve

Two or more user applications executing on one or more processors, each controlled by an operating system, share use of a list structure within a Structured External Storage (SES) facility to which each processor is connected. One of the applications registers interest in particular state transitions affecting one or more lists within the list structure, causing a process within the SES to notify the appropriate processor when a list operation causes the particular state transition, without interrupting processing on the processor. The application receives notice of the state transition by periodically polling a vector within the processor, or by receiving control when a test by the operating system of a summary indicator for the vector causes an application exit to be driven.

Data processing system and method for providing notification in a

Command quiesce function

Apparatus and method insuring that data objects used to maintain state information for shared data at a local central processing complex (CPC) are coherent with respect to state information maintained at a structured external storage facility (SES) over a link is valid. An error detector is attached to the CPC side of the link for detecting errors on the link, and, when an error is detected, setting a error state pending (ESP) latch to indicate that the link has failed and that the shared data in the local data object may be invalid because a message invalidating the data may not have been received by the CPC. In data processing operations, the ESP latch is interrogated by a central processor in the CPC to determine the health of the message path to the SES facility. A local cache vector reflecting the validity of the shared data in the local cache may then be interrogated to determine if the shared data in the local cache is valid. If a healthy path has continuously existed and the vector indicates that the local cache data is valid, the integrity of the data can be relied on.

Integrity of data objects used to maintain state information for shared

A Structured External Storage (SES) device/processor is connected to two or more DP systems, thereby loosely coupling the systems. The SES is capable of holding data objects of two distinct types (List objects and Cache objects), and communicates commands and command responses with the systems using a message protocol. A support facility within a processor on which a system is executing receives status indications from the SES without interrupting mainline system execution. Within the SES, a serialization mechanism allows more than one command to execute in parallel without loss of data object integrity, or command consistency. A forward completion mechanism sends to systems early notification of completion of certain commands, without permitting results inconsistent with this notification to be obtained by the systems. And a restart mechanism permits interrupted commands to be restarted by the initiating system or, in certain cases, by another system.

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Poughkeepsie, NY, United States of America

Audrey A Helffrich