Abstract: A method for recovering from an error in a multi-core storage-system component is disclosed. In one embodiment, such a method includes detecting an error in a first core of a multi-core component. The method determines whether the error was one of (1) detected by the first core; and (2) detected by a core other than the first core. In the event the error was detected by the first core and the error is recoverable, the first core recovers from the error without substantially impacting operation of other cores in the multi-core component. In the event the error was detected by a core other than the first core and the error is recoverable, a core other than the first core recovers from the error without substantially impacting operation of other cores in the multi-core component. A corresponding apparatus and computer program product are also disclosed.

Abstract: A method to minimize performance degradation during communication path failure in a data processing system, comprising a host computer, a storage controller, and a plurality of physical communication paths in communication with the host computer and the storage controller, where the method establishes a threshold communication path error rate, and determines an (i)th actual communication path error rate for an (i)th physical communication path, wherein that (i)th communication path is one of the plurality of physical communication paths. If the (i)th actual communication path error rate is greater than the threshold communication path error rate, the method discontinues use of the (i)th physical communication path.

Abstract: A system and method for recovering from logical path failures is set forth. More specifically, when a host detects a logical path failure, the host enters a path discovery mode of operation. If the host continues to detect a logical path failure while operating in the logical path discovery mode of operation, the host removes the logical path from a logical path mask, and the host does not use the removed logical path again. Additionally, the system and method facilitates recovery of the failed logical paths by using a plurality of logical path masks. A first mask is referred to as an intermediate failure logical path mask and a second mask is referred to as a permanent failure logical path mask.

Abstract: Provided are a method, system, and article of manufacture, in which a logical path is established between a control unit and a channel over a fiber channel connection. Code for persistent information unit pacing is loaded into the control unit and the channel. An indicator is set in node descriptors of the control unit and the channel to indicate concurrent enablement of persistent pacing while retaining the established logical path between the control unit and the channel.

Abstract: A storage control unit detects a change in a configuration of a plurality of logical subsystems included in the storage control unit. The storage control unit sends a notification, wherein the notification indicates the change in the configuration of the plurality of logical subsystems. The storage control unit receives data transfer requests directed at available logical subsystems in the storage control unit, wherein the available logical subsystems are determined based on the configuration of the plurality of logical subsystems.

Abstract: Provided are a system and article of manufacture for establishing and requesting status on a computational resource. An operation is performed to establish a computational resource, wherein the computational resource is not available until the establish operation is completed. A determination is made as to whether a status request to determine status of the computational resource is pending before the establish operation has completed. Indication is made to resubmit the status request if there is a status request for the computational resource pending before the establish operation has completed.

Abstract: Provided are a method, system, and article of manufacture, in which a logical path is established between a control unit and a channel over a fibre channel connection. Code for persistent information unit pacing is loaded into the control unit and the channel. An indicator is set in node descriptors of the control unit and the channel to indicate concurrent enablement of persistent pacing while retaining the established logical path between the control unit and the channel.

Abstract: Provided are a method, system, and article of manufacture, wherein a primary storage control unit receives an information unit from a remote host over a fiber channel connection, wherein persistent information unit pacing is implemented over the fiber channel connection. Information is maintained on how many large writes have been received at the primary storage control unit over at least one logical path established over the fiber channel connection between the primary storage control unit and the remote host, wherein a large write is an input/output (I/O) operation for which a number of data information units that are processed exceeds a default value of an information unit pacing credit.

Abstract: A system and method for recovering from logical path failures is set forth. More specifically, when a host detects a logical path failure, the host enters a path discovery mode of operation. If the host continues to detect a logical path failure while operating in the logical path discovery mode of operation, the host removes the logical path from a logical path mask, and the host does not use the removed logical path again. Additionally, the system and method facilitates recovery of the failed logical paths by using a plurality of logical path masks. A first mask is referred to as an intermediate failure logical path mask and a second mask is referred to as a permanent failure logical path mask.

Abstract: A method to minimize performance degradation during communication path failure in a data processing system, comprising a host computer, a storage controller, and a plurality of physical communication paths in communication with the host computer and the storage controller, where the method establishes a. threshold communication path error rate, and determines an (i)th actual communication path error rate for an (i)th physical communication path, wherein that (i)th communication path is one of the plurality of physical communication paths. If the (i)th actual communication path error rate is greater than the threshold communication path error rate, the method discontinues use of the (i)th physical communication path.

Abstract: Provided are a method, system, and article of manufacture, wherein a primary storage control unit receives an information unit from a remote host over a fibre channel connection, wherein persistent information unit pacing is implemented over the fibre channel connection. Information is maintained on how many large writes have been received at the primary storage control unit over at least one logical path established over the fibre channel connection between the primary storage control unit and the remote host, wherein a large write is an input/output (I/O) operation for which a number of data information units that are processed exceeds a default value of an information unit pacing credit.

Abstract: A storage control unit detects a change in a configuration of a plurality of logical subsystems included in the storage control unit. The storage control unit sends a notification, wherein the notification indicates the change in the configuration of the plurality of logical subsystems. The storage control unit receives data transfer requests directed at available logical subsystems in the storage control unit, wherein the available logical subsystems are determined based on the configuration of the plurality of logical subsystems.

Abstract: Provided are a system and article of manufacture for establishing and requesting status on a computational resource. An operation is performed to establish a computational resource, wherein the computational resource is not available until the establish operation is completed. A determination is made as to whether a status request to determine status of the computational resource is pending before the establish operation has completed. Indication is made to resubmit the status request if there is a status request for the computational resource pending before the establish operation has completed.

Abstract: A storage control unit detects a change in a configuration of a plurality of logical subsystems included in the storage control unit. The storage control unit sends a notification, wherein the notification indicates the change in the configuration of the plurality of logical subsystems. The storage control unit receives data transfer requests directed at available logical subsystems in the storage control unit, wherein the available logical subsystems are determined based on the configuration of the plurality of logical subsystems.

Abstract: Provided are a method, system, and program for establishing and requesting status on a computational resource. An operation is performed to establish a computational resource, wherein the computational resource is not available until the establish operation is completed. A determination is made as to whether a status request to determine status of the computational resource is pending before the establish operation has completed. Indication is made to resubmit the status request if there is a status request for the computational resource pending before the establish operation has completed.

Abstract: Provided are a method, system, and program for simulating I/O requests to test a system coupled to an adaptor having a port used for transmitting and receiving I/O requests to the system. A user test command is received indicating an I/O test object. The adaptor processes the I/O test object indicated in the user test command to generate a sequence of simulated I/O requests and transmits the generated simulated I/O requests to the system.

Abstract: Provided are a method, system, and program for simulating I/O requests to test a system coupled to an adaptor having a port used for transmitting and receiving I/O requests to the system. A user test command is received indicating an I/O test object. The adaptor processes the I/O test object indicated in the user test command to generate a sequence of simulated I/O requests and transmits the generated simulated I/O requests to the system.

Abstract: Provided are a method, system, and program for establishing and requesting status on a computational resource. An operation is performed to establish a computational resource, wherein the computational resource is not available until the establish operation is completed. A determination is made as to whether a status request to determine status of the computational resource is pending before the establish operation has completed. Indication is made to resubmit the status request if there is a status request for the computational resource pending before the establish operation has completed.

Abstract: Disclosed is a system, method, and program for managing I/O operations transmitted from a computer system to a processing unit. The processing unit manages access to a storage device and executes the I/O operation against the storage device. The processing unit receives indication that a request to connect between the processing unit and the computer system failed. Upon receiving a subsequent I/O operation from the computer system after receiving indication that the connect request failed, the processing unit returns busy to the computer system initiating the subsequent I/O operation in response to receiving indication that the connect request failed. The connect request is retried after returning busy.

Abstract: A method for establishing bilateral communications over a single ESCON link coupling a pair of control units. The method steps include (a) permitting link address acquisition between directly connected link-level facilities that simultaneously assume the role of a master control unit in a peer-to-peer remote copy (PPRC) configuration, (b) resolving conflicting device-level frames that initiate a path to a device (also termed an I/O connection), and (c) dynamically determining the role assumed by a link-level facility (master or slave) when a single logical path is shared.