International Business Machines Corporation

Kenneth M Trowell

Harry M Yudenfriend

John R Flanagan

Matthew J Kalos

Giles R Frazier

Louis William Ricci

Robert J Dugan

Jeffrey Paul Kubala

Charles W Gainey, Jr

Dale Francis Riedy, Jr

Richard Anthony Ripberger

Juan A Coronado

Kenneth J Oakes

Scott M Carlson

Patricia G Driever

Frank William Brice

Eugene P Hefferon

Charles E Shapley

Ira Glenn Siegel

Roberto J Sanchez

Provided are a method, system, and article of manufacture for assigning alias addresses to base addresses. An assignment is provided of base addresses to the devices. The base addresses are used to access the devices assigned to the base addresses. An assignment is provided of a plurality of alias addresses to an alias address pool. The alias addresses in the alias address pool are capable of being dynamically assigned to the devices to service I/O requests to the devices. An Input/Output (I/O) request to access one target device comprising one of the devices is processed. A determination is made as to whether the base address assigned to the target device is available. One alias address is assigned to the target device in response to determining that the base address is not available. The I/O request is issued to the assigned alias address to transmit the request to the target device.

Assigning alias addresses to base addresses

A computer Input/Output system having a fabric, a control unit (CU) and a host computer including a channel, the channel having a channel port connected by a first link to a channel neighbor port of the fabric, and the control unit having a CU port connected by a second link to a CU neighbor port on the fabric. Then an error is detected in the link or protocol between the channel and the control unit, error data are reported to the channel by the channel, the channel port, the channel neighbor port, the control unit, the CU port and the CU neighbor port and sent to the channel. The error data are provided to the host computer for analysis.

Transfer of error-analysis and statistical data in a fibre channel input/output system

A computer Input/Output system having a fabric, a control unit (CU) and a host computes including a channel, the channel having a channel port connected by a first link to a channel neighbor port of the fabric, and the control unit having a CU port connected by a second link to a CU neighbor port on the fabric. When an error is detected in the link or protocol between the channel and the control unit, after a retry of the failing operation is performed, error data are reported to the channel by the channel, the channel port, the channel neighbor port, the control unit, the CU port and the CU neighbor port and sent to the channel. The error data are provided to the host computer for analysis.

Transfer of error-analysis and statistical data after retry in a fibre channel input/output system

A computer Input/Output system having a fabric, a control unit (CU) and a host computer including a channel, the channel having a channel port connected by a first link to a channel neighbor port of the fabric, and the control unit having a CU port connected by a second link to a CU neighbor port on the fabric. When an error is detected in the link or protocol between the channel and the control unit, error data are reported to the channel by the channel, the channel port, the channel neighbor port, the control unit, the CU port and the CU neighbor port and sent to the channel. The error data are provided to the host computer for analysis.

In an environment employing a fabric, such as a cascading switch network, a predictable input/output (I/O) configuration is provided. The I/O configuration explicitly specifies the one or more peripheral units accessible by a program, such as an operating system. Other peripheral units not specified in the I/O configuration are not accessible, thus, providing a secure environment.

Predictably defining input/output configurations for environments employing fabrics

Validation of a re-initialized CTC connection between a first channel and a second channel is provided in a computing environment in which a CTC CU function can be provided in either channel after initialization of the CTC connection and can move from one channel to the other after re-initialization of the connection. After initialization, a newly formatted CDR having a device NED and a specific NEQ is stored. After re-initialization, a current CDR with the same format is obtained. The re-initialized CTC connection is validated if the stored set of NED and NEQ values match the current values, in any order.

Technique for validating a re-initialized channel-to-channel connection

A method and apparatus for specifying offsets from an external time reference (ETR) for selected logical partitions of a partitioned information handling system. Each logical partition has a logical time-of-day (TOD) clock which may be set independently of the host system clock by specifying an epoch offset from the host clock. A system operator is presented with a display panel in which the operator may specify the magnitude and sign of an ETR offset for each logical partition selected to have an ETR offset. Each logical partition, upon being activated, issues a Store Clock (STCK) instruction to read its own logical TOD clock as well as a Store ETR (STETR) instruction to read the ETR. If the logical partition has a specified ETR offset, the logical partition manager simulates the STETR instruction by adding or subtracting the ETR offset to the real ETR time and returning the modified value to the partition; otherwise, the logical partition manager returns the real ETR time to the partition. If the read ETR time (as returned by the STETR instruction) differs from the read logical clock time, the logical partition issues a Set Clock (SCK) instruction to reset the logical partition clock to the ETR time. The logical partition manager simulates this latter instruction by computing the difference between the two times and storing the difference in an epoch offset field for the partition. The invention permits sets of logical partitions to be synchronized to different clock values, either for test purposes or operation in different time zones.

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Terrey Hills, Australia

Kenneth M Trowell