Abstract: Provided are a computer program product, system, and method for managing I/O requests to a storage array of storage devices in a machine having a processor node and device adaptor. In response to initiating a rebuild of data in the storage array, the device adaptor determines whether a remaining fault tolerance at the storage array comprises a non-zero fault tolerance that permits at least one further storage device to fail and still allow recovery of data stored in the storage array. In response to determining that the remaining fault tolerance is a zero fault tolerance that does not permit at least one storage device to fail and allow recovery of data, the device adaptor sends a message to the processor node to cause the processor node to initiate an emergency protocol to terminate a mission critical operation when the processor node is performing the mission critical operation.

Abstract: Provided are a computer program product, system, and method for reducing a rate at which data is mirrored from a primary server to a secondary server. A determination is made as to whether a processor utilization at a processor managing access to the secondary storage exceeds a utilization threshold. If so, a determination is made as to whether a specified operation at the processor is in progress. A message is sent to the primary server to cause the primary server to reduce a rate at which data is mirrored from the primary server to the secondary server in response to determining that the specified operation is in progress.

Abstract: One general aspect of device reservation state preservation in accordance with the present description, provides for an intermediate reservation state, referred to herein as a “peer” reservation state, which may be maintained by a storage controller in the event of a total loss of communication connectivity to the reserving host so long as a peer or partner storage controller of a mirror relationship still has communication connectivity to the host. The peer reservation state as used herein, is a reservation state intermediate between a full reservation state for a device, and a fully released state in which a reservation of the device has been completely released. Other features and aspects may be realized, depending upon the particular application.

Abstract: One general aspect of device reservation state synchronization in accordance with the present description, device reservation management logic ensures synchronization of reservation states of primary and secondary volumes of a mirror relationship in the event of a change in the state of the mirroring relationship such as achieving full data synchronization between the volumes. Other features and aspects may be realized, depending upon the particular application.

Abstract: One general aspect of device reservation management in accordance with the present description, is directed to a host issuing I/O data requests to a primary device which synchronously mirrors data to a secondary data storage device wherein both devices are reserved for exclusive use by the host for I/O data requests. In response to a loss of communication connectivity on all paths to the primary storage controller controlling the primary device, the host confirms whether a communication path to the primary device has been established and whether the primary device remains reserved to the host. Upon successful confirmations, the reservation of the primary device is repaired such that I/O data requests to the reserved primary device continue. Other features and aspects may be realized, depending upon the particular application.

Abstract: In one embodiment, a computer program product for managing a reserve command includes a computer readable storage medium having program code embodied therewith, the program code readable and/or executable by a processor to receive, by the processor, a request to access a data set on one or more volumes of at least one direct access storage device (DASD), the request including a reserve command, and each of the one or more volumes including a consecutive set of one or more tracks of the at least one DASD, and reserve one or more extents of the at least one DASD while reserving less than a volume of the at least one DASD and not allowing any other entity than an entity which requested the reserve to access the one or more extents of the at least one DASD that have been reserved.

Abstract: A determination is made that data stored in an extent of a first storage resource is to be moved to an extent of a second storage resource. Operations that are still awaiting to start execution in the first storage resource after the data stored in the extent of the first storage resource has been moved to the extent of the second storage resource, are configured for execution in the second storage resource.

Abstract: Provided are a computer program product, system, and method for processing a health condition message on a health condition to determine whether to perform a swap operation. A health condition message is received from a first server indicating an estimated Input/Output (I/O) delay to access a first storage resulting from a health condition experienced at the first server. A determination is made as to whether the estimated I/O delay exceeds a threshold response time for the first storage. A swap operation is performed to redirect I/O requests to data from the first server to the second server to access the data at the second storage in response to determining that the estimated I/O delay exceeds the threshold response time.

Abstract: One general aspect of device reservation state preservation in accordance with the present description, provides for an intermediate reservation state, referred to herein as a “peer” reservation state, which may be maintained by a storage controller in the event of a total loss of communication connectivity to the reserving host so long as a peer or partner storage controller of a mirror relationship still has communication connectivity to the host. The peer reservation state as used herein, is a reservation state intermediate between a full reservation state for a device, and a fully released state in which a reservation of the device has been completely released. Other features and aspects may be realized, depending upon the particular application.

Abstract: A plurality of cores are maintained in a processor complex. A core of the plurality of cores is reserved for execution of critical tasks, wherein it is preferable to prioritize execution of critical tasks over non-critical tasks. A scheduler receives a task for scheduling in the plurality of cores. In response to determining that the task is a critical task, the task is scheduled for execution in the reserved core.

Abstract: A plurality of processing entities are maintained in a processor complex. In response to determining that a task is a critical task, the critical task is dispatched to a scheduler, wherein it is preferable to prioritize execution of critical tasks over non-critical tasks. In response to dispatching the critical task to the scheduler, the scheduler determines which processing entity of the plurality of processing entities has a least amount of processing remaining to be performed for currently scheduled tasks. Tasks queued on the determined processing entity are moved to other processing entities, and the currently scheduled tasks on the determined processing entity are completed. In response to moving tasks queued on the determined processing entity to other processing entities and completing the currently scheduled tasks on the determined processing entity, the critical task is dispatched on the determined processing entity.

Abstract: Provided are a computer program product, system, and method for generating a health condition message on a health condition detected at a first server to send to a host system accessing the first server. A determination is made of a health condition with respect to access to a first storage. A determination is made of an estimated Input/Output (I/O) delay to access the first storage resulting from the determined health condition. A health condition message is generated indicating the estimated I/O delay. The health condition message is transmitted to the host system, wherein the host system uses the estimated I/O delay to determine whether to perform a swap operation to redirect host I/O requests to data from the first server to a second server.

Abstract: A determination is made that data stored in an extent of a first storage resource is to be moved to an extent of a second storage resource. Operations that are still awaiting to start execution in the first storage resource after the data stored in the extent of the first storage resource has been moved to the extent of the second storage resource, are configured for execution in the second storage resource.

Abstract: Provided are a computer program product, system, and method for processing a health condition message on a health condition to determine whether to perform a swap operation. A health condition message is received from a first server indicating an estimated Input/Output (I/O) delay to access a first storage resulting from a health condition experienced at the first server. A determination is made as to whether the estimated I/O delay exceeds a threshold response time for the first storage. A swap operation is performed to redirect I/O requests to data from the first server to the second server to access the data at the second storage in response to determining that the estimated I/O delay exceeds the threshold response time.

Abstract: A plurality of extents of a plurality of logical volumes are stored in a plurality of ranks, where each logical volume of the plurality of logical volumes is comprised of a plurality of extents including a first extent. In response to determining that first extents stored in each rank of the plurality of ranks have become unbalanced in number in the plurality of ranks, a balancing of the first extents in the plurality of ranks is performed by redistributing the first extents in the plurality of ranks.

Abstract: A method for concurrently erasing data on a processor and preparing the processor for removal from a computing system is disclosed. In one embodiment, such a method includes determining tasks queued to be executed on a processor and reassigning the tasks to a different processor, such as to a different processor in the same cluster as the processor. The method further prevents new tasks from being assigned to the processor. The method waits for currently executing tasks on the processor to complete. Once the currently executing tasks are complete, the method initiates a cache-hostile job on the processor to evict entries in cache of the processor. Once the cache-hostile job is complete, the method enables the processor to be removed from a computing system such as a storage system controller. A corresponding system and computer program product are also disclosed.

Abstract: Mechanisms for improving computing system performance by a processor device. System resources are organized into a plurality of groups. Each of the plurality of groups is assigned one of a plurality of predetermined task pools. Each of the predetermined task pools has a plurality of tasks. Each of the plurality of groups corresponds to at least one physical boundary of the system resources such that a speed of an execution of those of the plurality of tasks for a particular one of the plurality of predetermined task pools is optimized by a placement of an association with the at least one physical boundary and the plurality of groups.

Abstract: A determination is made that data stored in an extent of a first storage resource is to be moved to an extent of a second storage resource. Operations that are still awaiting to start execution in the first storage resource after the data stored in the extent of the first storage resource has been moved to the extent of the second storage resource, are configured for execution in the second storage resource.

Abstract: A method for analyzing and optimizing legacy program code is disclosed. In one embodiment, such a method includes logically dividing legacy program code into multiple sections and possibly subsections. The method then instruments each section with a counter that increments a value each time the respective section is executed. The legacy program code is then executed over a specified period of time on a specified number of test systems. The values are then gathered from the counters and analyzed to determine relative importance of the sections. In certain embodiments, this analysis generates a list of sections that are dead. The method then removes, from the legacy program code, sections that are dead. A corresponding system and computer program product are also disclosed.

Abstract: Provided are a computer program product, system, and method for fixing anomalies in a preserved data structure used to generate a temporary data structure during system initialization. A preserved data structure in persistent storage is used to build a temporary data structure in a memory of the computing system during initialization of the computing system. The temporary data structure represents computational resources in the computing system and is rebuilt from the preserved data structure during the initialization. The preserved data structure and the temporary data structure are processed to determine whether the preserved data structure includes at least one anomaly that would result in rebuilding the temporary data structure with an error. Information on the preserved data structure and the temporary data structure having the anomaly are processed to determine modifications to correct the preserved data structure. The determined modifications are processed to correct the preserved data structure.