International Business Machines Corporation

Fred Hutchinson Cancer Center

Thomson Industries, Inc.

Fred Hutchinson Cancer Research Center

Scott M Carlson

Harry M Yudenfriend

Roger Gregory Hathorn

Dale Francis Riedy, Jr

John R Flanagan

Matthew J Kalos

Daniel Francis Casper

Louis William Ricci

Dennis J Dahlen

Donald Crabtree

Denise M Sevigny

Kenneth J Oakes

Leslie W Wyman

Tan Lu

Ronald Morton Smith, Sr

Judith A Wierbowski

William J Rooney

Michel H T Hack

John S Trotter

Greg A Dyck

Gustav E Sittmann, Iii

Catherine C Huang

Noshir R Dhondy

David Arlen Elko

Renato John Recio

Jeffrey William Palm

David E Whitney

Li Feng Zhang

Daniel Gene Eisenhauer

Charles W Gainey, Jr

Richard K Errickson

Ugochukwu Charles Njoku

Mark P Bendyk

Sandy K Kao

Susan Kay Candelaria

Beth A Glendening

Jeffrey Paul Kubala

Frank William Brice

Aaron C Brown

Charles E Shapley

Michel Henri Théodore Hack

Janet R Easton

Marten J Halma

Kevin J Gildea

Michel Henri Theodore Hack

Stephen P Cherniak

Gustav E Sittmann

Geoffrey E Miller

Marisa Freidhof

Louis C Ricci

Matthew Stephens

Jonathan D Bradbury

Scott Brady Compton

Patricia G Driever

Bret Wayne Holley

Gregory John Tevis

Matthew Richard Craig

Eugene P Hefferon

Georgette L Kurdt

Hans-Helge Lehmann

Kenneth M Trowell

Gustav E Sittman, Iii

Trevor E Carlson

Elaine Ostrander

Roberto J Sanchez

Frank Dalessandro

Ughochukwu C Njoku

Michael H T Hack

Leonid Kruglyak

Heidi G Parker

Lisa V Kim

Tiffany B Malek

Nathan B Sutter

William M Sakal

Michael Ht Hack

Matthew Joseph Kalos

Allison Ng

Gustav Sittmann Iii

Njoku Ugochukwu

Aaron Ches Brown

Disclosed are a method of and system for providing time synchronization among first and second computer systems, where each of the computer systems includes hardware, operating system software and a layer of microcode operating between said hardware and said software. The method comprises the steps of using the microcode of the first computer system to provide a first timestamp, using the microcode of the second computer system to provide a second timestamp and a third timestamp, and using the microcode of the first computer system to provide a fourth timestamp. The method comprises the further steps of using the first, second, third and fourth timestamps to determine a timing difference between the first and second computer systems, and adjusting the timing among said first and second computer systems on the basis of said determined timing difference. Preferably, the first and second computer systems are connected together by a point-to-point link; and the first timestamp is sent from the first computer system to the second computer system, and the second and third timestamps are sent from the second computer system to the first computer system over that point-to-point link.

Method and system for time synchronization among systems using parallel sysplex links

An Extended Input/output (I/O) measurement word facility is provided. Provision is made for emulation of the Extended I/O measurement word facility. The facility provides for storing measurement data associated with a single I/O operation in an extended measurement word associated with an I/O response block. In a further aspect, the stored data may have a resolution of approximately one-half microsecond.

Extended input/output measurement word facility for obtaining measurement data in an emulated environment

A computer program product is provided for performing a method that includes receiving a command message at a control unit from a channel subsystem in a host computer system, the command message including a command for data to be transferred from the host computer system to an I/O device. The method also includes receiving a data transfer message at the control unit, the data transfer message having an amount of the data to be transferred that is less than or equal to a maximum amount of data, the maximum amount of data corresponding to a number of buffers associated with the control unit and a size of each of the number of buffers, the number of buffers indicated by a buffer credit value maintained in the host computer system, and the size indicated by a buffer size value sent from the control unit and maintained in the host computer system.

Transport mode data transfer between a channel subsystem and input/output devices

A protocol for communicating with the timing facility used in a data processing network to provide synchronization is provided via the execution of a machine instruction that accepts a plurality of commands. The interaction is provided through the use of message request blocks and their associated message response blocks. In this way timing parameters may be determined, modified and communicated. This makes it much easier for multiple servers or nodes in a data processing network to exist as a coordinated timing network and to thus more cooperatively operate on the larger yet identical data files.

Channel subsystem server time protocol commands

A stratum-1 configuration for a timing network is defined. The stratum-1 configuration includes a single active stratum-1 server usable in ensuring that the servers in the network use the same primary reference time to synchronize their clocks. The servers in the network are synchronizing to the same root primary reference time and synchronization accuracy is not dependent on the quality of an external time source or of the existence of an external time source at the stratum-1 server.

Employing configuration information to determine the role of a server in a coordinated timing network

A computer program product is provided for performing a method including: receiving transmission data over a selected time interval for each of a plurality of communication paths; calculating an average round-trip transmission time for each of the plurality of communication paths over the time interval; comparing an average round-trip transmission time for a communication path having the highest average round-trip transmission time to a threshold value and to a multiple of an average round-trip transmission time for a communication path having the lowest average round-trip transmission time; and determining, based on a result of comparing the highest round-trip transmission time to the threshold value and to a multiple of the lowest round-trip transmission time, whether the time period indicates a delay in communication between the I/O subsystem and the control unit requiring at least one of a monitoring action and a recovery action.

Monitoring network performance and detecting network faults using round trip transmission times

A computer program product is provided for performing an input/output (I/O) operation at a host computer system configured for communication with a control unit. The computer program product is configured to perform: sending a transport mode command message from a channel subsystem to the control unit, the command message including a command for data to be transferred to an I/O device controlled by the control unit; and sending a data transfer message to the control unit, the data transfer message having an amount of the data to be transferred, the amount of the data being less than or equal to a maximum amount of data, the maximum amount of data corresponding to a number of buffers associated with the control unit and a size of each of the number of buffers, the number and the size indicated by a value maintained in the host computer system.

A method of processing communications includes: receiving transmission data over a selected time interval for each of a plurality of communication paths between a host processor and a control unit configured to control at least one I/O device; calculating an average round-trip transmission time for each of the communication paths over the time interval; comparing an average round-trip transmission time for a communication path having the highest average round-trip transmission time to a threshold value and to a multiple of an average round-trip transmission time for a communication path having the lowest average round-trip transmission time; and determining, based on comparing the highest round-trip transmission time to the threshold value and to a multiple of the lowest round-trip transmission time, whether the time period indicates a delay in communication between the I/O subsystem and the control unit requiring at least one of a monitoring action and a recovery action.

A computer program product is provided for performing an input/output (I/O) operation initiated by an I/O operation instruction at a host computer system configured for communication with a control unit. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing: receiving, by the control unit, a transport mode command message from a channel subsystem of the host computer system, the command message include a command for data to be transferred between the host computer system and an I/O device controlled by the control unit; and sending a command retry message to the channel subsystem, the command retry message including a request that the command message be re-sent to the control unit and a reason code indicating a reason for the request.

Facilitating transport mode data transfer between a channel subsystem and input/output devices

Server time protocol (STP) messages and methods of exchange thereof are provided for facilitating synchronization of processing units of a timing network. The STP messages include exchange time parameters (XTP) commands and responses, and STP control (STC) commands and responses. XTP message exchange processing includes: generating an XTP message command at a first processing unit including a command transmit timestamp field set by the first processing unit and a command receive timestamp field which is unset by the first processing unit; transmitting the XTP message command to a second processing unit; setting the command receive timestamp field in the XTP command with the time the XTP command is received at the second processing unit; and generating an XTP message response at the second processing unit, the message response including the command transmit timestamp set by the first processing unit and the command receive timestamp set by the second processing unit.

Server time protocol messages and methods

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Tucson, AZ, United States of America

Scott M Carlson