Abstract: 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.

Abstract: A failsafe recovery capability for a Coordinated Timing Network. The recovery capability facilitates recovery when communication is lost between two servers of the coordinated timing network. The capability includes checking another system's status in order to determine what action is to be taken. The status includes the stratum level of the servers and a version number indicating the code level of the servers.

Abstract: A computer program product, apparatus, and method for providing exception condition feedback at a control unit to a channel subsystem in an I/O processing system are provided. 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 a method. The method includes receiving a command message at the control unit from the channel subsystem, and detecting an exception condition in response to unsuccessful execution of at least one command in the command message. The method further includes identifying a termination reason code associated with the exception condition, writing the termination reason code to a response message, and sending the response message to the channel subsystem.

Abstract: A computer program product, apparatus, and method are provided for determining a state of an input/output (I/O) operation in an I/O processing system. A request from a channel subsystem is received at a control unit for performing the I/O operation. After a predetermined amount of time passes without the I/O operation completing, an interrogation request is received from the channel subsystem at the control unit for determining the state of the I/O operation. A response is sent from the control unit to the channel subsystem indicating the state of the I/O operation in response to the interrogation request. The response also includes information regarding a state of an I/O device executing the I/O operation and information indicating a state of the control unit controlling the I/O device executing the I/O operation.

Abstract: In a networked data processing system, the updating of timing parameters is carried out via a process in which the detection of the loss of communications with the network is not immediately employed as an indication of parameter invalidity but rather the process employs a system specific delay which permits actions such as server or link recovery to occur without necessitating the declaration of timing parameter invalidity.

Abstract: 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.

Abstract: 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.

Abstract: A primary time server of a Coordinated Timing Network remains as current time server, even if time code information of the primary time server is unavailable. The primary time server receives the necessary or desired timing information from a secondary time server and uses that information to maintain time synchronization within the Coordinated Timing Network.

Abstract: Disclosed are a method and system for calculating clock offset and skew between two clocks in a computer system. The method comprises the steps of sending data packets from a first processing unit in the computer system to a second processing unit in the computer system, and sending the data packets from the second processing unit to the first processing unit. First, second, third and fourth time stamps are provided to indicate, respectively, when the packets leave the first processing unit, arrive at the second processing unit, leave the second processing unit, and arrive at the first processing unit. The method comprises the further steps of defining a set of backward delay points using the fourth time stamps, and calculating a clock offset between clocks on the first and second processing units and clock skews of said clocks using said set of backward delay points.

Abstract: A computer program product, an apparatus, and a method for processing communications between a target and an initiator an input/output processing system are provided. 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 a method. The method includes: sending a message between the initiator and the target, the message requesting suspension of input/output operations between the initiator and the target for a period of time, the period of time being defined by the message; and responsive to the message, suspending input/output operation messages for the period of time.

Abstract: A computer program product, an apparatus, and a method for processing communications between a control unit and a channel subsystem in an input/output processing system are provided. 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 a method.

Abstract: Disclosed are a method and system to estimate the maximum error in the clock offset and skew estimation between two clocks in a computer system. The method comprises the steps of obtaining a first set of data values representing a forward delay between the first and second clocks, and obtaining a second set of data values representing a negative backward delay between the first and second clocks. The method comprises the further step of forming a lower convex hull for said first set of data values, and forming an upper convex hull for said second set of data values. First and second parallel lines are formed between the upper and lower convex hulls, and these parallel lines are used to estimate the worst case error for the offset, skew rate and dispersion of said first and second clocks.

Abstract: A technique for establishing a logical path between two servers in a coordinated timing network of a processing environment is provided. The technique includes the exchange of command and response message pairs by a server and an attached server, via a physical link. The server transmits a command message to an attached server to establish a server-time-protocol (STP) logical path and receives a response from the attached server. The technique also includes the server receiving a request transmitted by the attached server to establish an STP logical path to the server and transmitting a response to the attached server's request. A logical path between the server and the attached server is established if the attached server's response indicates that the server's request was accepted by the attached server and if the server's response indicates that the attached server's request was accepted by the server.

Abstract: A system for using a virtual switch in a network. In response to a switch connecting to a network, network configuration data is read to determine whether the switch is part of a virtual switch. In response to determining that the switch is part of the virtual switch, a priority number for the switch is sent to other switches connected to the network. Priority numbers are received from the other switches. It is determined whether the switch has a highest priority number. In response to determining that the switch does have the highest priority number, the switch is selected to be a master switch for the virtual switch. Then, domain identification data for the virtual switch is sent to the other switches. Afterward, the switch and the other switches respond to requests over the network as one domain identified by the domain identification data.

Abstract: 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.

Abstract: A timing network is provided that includes a plurality of servers. The servers of the network obtain information used to maintain the servers in time synchronization, thus ensuring the integrity of the servers.

Abstract: Recovery is provided in a timing network. A configuration is defined for that network, and in that configuration, an active primary server is identified that provides a clock source for the network. Additionally, an alternate server is identified that can perform the role of the active primary server, should the active primary server fail. In response to a failure of the primary server, the alternate server detects the failure and performs takeover of the primary server.

Abstract: A timing network is provided that includes a plurality of servers. The servers of the network obtain information used to maintain the servers in time synchronization, thus ensuring the integrity of the servers.

Abstract: 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.

Abstract: A Fibre Channel over Ethernet (FCoE) device obtains knowledge of the configuration of an attached Ethernet fabric from data fields within a frame header during a fabric initialization or login (FLOGI) process. FCoE N_Ports obtain similar information during the port initialization or login (PLOGI) process. The FCoE device may provide network management services to attached FCoE devices. Embodiments include a management module or processor within an FCoE N_Port. The management module or processor receives a frame having a header and validates and extracts information associated with an Ethernet fabric from the FCoE N_Ports and in order to provide management services based on the information associated with the Ethernet fabric. The FCoE N_Port communicatively couples to at least one additional FCoE N_Port through the Ethernet fabric. The FCoE N_Ports may be implemented within a disc storage drive, a host bus adapter, and/or an FCoE switch.