Abstract: Provided are a computer program product, system, and method for maintaining data structures in a virtual memory comprised of a plurality of heterogeneous memory devices. Access counts are maintained for a plurality of data structures stored in a first level memory device. A determination is made of data structures in the first level memory device having lowest access counts. The determined data structures are deleted from the first level memory device and retaining copies of the data structures in a second level memory device, wherein the first level memory device has lower latency than the second level memory device.

Abstract: Provided are computer program product, system, and method for managing data structures in a plurality of memory devices that are indicated to demote after initialization of the data structures. Indication is made to data structures to demote after initialization from a first level memory device to a second level memory device. The first level memory device has lower latency than the second level memory device. In response to completing initialization of the data structures in the first level memory device, the data structures indicated to demote after initialization are copied from the first level memory device to the second level memory device and removing the data structures indicate to move after initialization from the first level memory device.

Abstract: Provided are a computer program product, system, and method for managing swappable data structures in a plurality of memory devices based on access counts of the data structures. Data structures indicated as swappable are updated less frequently than most frequently updated data structures. Data structures not indicated as swappable are maintained in a first level memory device and not moved to a second level memory device. The first level memory device has lower latency than the second level memory device. Access counts are maintained for the data structures stored in the first level memory device that are indicated as swappable. Data structures are selected in the first level memory device having lowest access counts. The selected data structures are removed from the first level memory device and retained in the second level memory device.

Abstract: A plurality of interfaces that share a plurality of resources in a storage controller are maintained. In response to an occurrence of a predetermined number of operations associated with an interface of the plurality of interfaces, an input is provided on a plurality of attributes of the storage controller to a machine learning module. In response to receiving the input, the machine learning module generates an output value corresponding to a number of resources of the plurality of resources to allocate to the interface in the storage controller.

Abstract: A machine learning module receives inputs comprising attributes of a storage controller, wherein the attributes affect allocation of a plurality of resources to a plurality of interfaces. In response to a predetermined number of I/O operations occurring in the storage controller, a generation is made via forward propagation through a plurality of layers of the machine learning module, of an output value corresponding to a number of resources to allocate to an interface. A margin of error is calculated based on comparing the generated output value to an expected output value that is generated from an indication of a predetermined function based at least on a number of I/O operations that are waiting for a resource and a number of available resources. An adjustment is made of weights of links that interconnect nodes of the plurality of layers via back propagation, to reduce the margin of error.

Abstract: A method for managing storage functions in a data replication environment is disclosed. In one embodiment, such a method includes continually monitoring for changes to a storage configuration at a secondary site. Upon detecting changes to the storage configuration at the secondary site, the method transmits remote metadata describing the changes to the primary site and stores the remote metadata at the primary site. The method then initiates a storage management function at the primary site which is mirrored to the secondary site. In order to perform the storage management function, the method reads the remote metadata at the primary site to determine the storage configuration at the secondary site. The method then performs the storage management function at the primary site in a way that takes into account the storage configuration at the secondary site.

Abstract: A method for managing storage functions in a data replication environment is disclosed. In one embodiment, such a method includes continually monitoring for changes to a storage configuration at a secondary site. Upon detecting changes to the storage configuration at the secondary site, the method transmits remote metadata describing the changes to the primary site and stores the remote metadata at the primary site. The method then initiates a storage management function at the primary site which is mirrored to the secondary site. In order to perform the storage management function, the method reads the remote metadata at the primary site to determine the storage configuration at the secondary site. The method then performs the storage management function at the primary site in a way that takes into account the storage configuration at the secondary site. A corresponding apparatus, system, and computer-readable medium are also disclosed and claimed herein.

Abstract: Embodiments of the disclosure relate to setting up a logical path group identification for multiple data storage devices. An aspect of the disclosure concerns a computer implemented method that comprises receiving a host command to establish a group of connection paths between the host and a plurality of storage devices, identifying the group of connection paths, adding each one of the storage devices to the group of connection paths, and reporting to the host those storage devices that could not be successfully added to the group of connection paths. The method maintains host access security to the storage devices by not grouping a device when it is a reset event state.

Abstract: A method for invalidating metadata associated with a target count-key-data (CKD) volume is disclosed. The method initially receives a command for a target CKD volume. The command is either an “establish” command for establishing a point-in-time copy relationship, or a “withdraw” command for withdrawing a point-in-time copy relationship. The method determines a track range, spanning a number of data tracks in the CKD volume, associated with the command. Each data track in the track range is associated with a metadata track. For each metadata track whose associated data tracks are fully contained in the track range, the method performs a first procedure. For each metadata track whose associated data tracks are not fully contained in the track range, the method performs a second procedure different from the first procedure. A corresponding apparatus and computer program product are also disclosed.

Abstract: To prevent loss of a data volume by unintended deletion, including various versions of the data volume, the data is preserved, and, when needed, is regenerated at a different volume address than that of the deleted volume. In a computer-implemented data storage system, a method responds to a received command to delete a volume of data identified by a volume address, preserving data of the volume prior to deletion, and generates a unique token associated with the volume and version of the volume as of the deletion. The unique token is communicated as associated with the received delete command. The method responds to a received command to regenerate the data of the deleted volume, generating a command to find the data identified by the unique token, and creating a new, different, volume address for the data of the preserved deleted volume, thereby keeping both volume versions.

Abstract: A method, apparatus, and computer program product for handling a failure condition in a storage controller is disclosed. In certain embodiments, a method may include initially detecting a failure condition in a storage controller. The failure condition may be associated with a specific host and a specific storage device connected to the storage controller. The method may further include determining a failure ID associated with the failure condition. Using the failure ID, en entry may be located in a data collection and recovery table. This entry may indicate one or more data collection and/or recovery processes to execute in response to the failure condition. The method may then execute the data collection and/or recovery processes indicated in the entry. While executing the data collection and/or recovery processes, connectivity may be maintained between hosts and storage devices not associated with the failure condition.

Abstract: Embodiments of the disclosure relate to setting up a logical path group identification for multiple data storage devices. An aspect of the disclosure concerns a computer implemented method that comprises receiving a host command to establish a group of connection paths between the host and a plurality of storage devices, identifying the group of connection paths, adding each one of the storage devices to the group of connection paths, and reporting to the host those storage devices that could not be successfully added to the group of connection paths. The method maintains host access security to the storage devices by not grouping a device when it is a reset event state.

Abstract: A host reserves a device controlled by a controller that is coupled to the host. The controller starts a first timer, in response to a completion of input/output (I/O) operations on the device by the host, wherein the host continues to reserve the device after the completion of the I/O operations. The controller sends a notification to the host after an expiry of the first timer, wherein the notification requests the host to determine whether the device should continue to be reserved by the host. The controller starts a second timer, in response to receiving an acknowledgement from the host that the notification has been received by the host, wherein reservation status of the device reserved by the host is determined by the controller on or prior to an expiry of the second timer.

Abstract: A method for identifying the cause of degraded I/O performance between a host system and a storage controller includes initially monitoring I/O performance between the host system and the storage controller. The method further detects degraded I/O performance between the host system and the storage controller using any suitable technique. Once degraded I/O performance is detected, the method determines the cause of the degraded I/O performance by analyzing historical configuration records in the storage controller. These historical configuration records enable the storage controller to correlate the degraded I/O performance with configuration changes in the storage controller and/or the connected host systems. The method then notifies one or more host systems of the cause of the degraded I/O performance. A corresponding apparatus and computer program product are also disclosed herein.

Abstract: A method for combining partial records into a single direct memory access (DMA) operation for a count key data (CKD) protocol in a computer environment is provided. In an initiator processor of the computer environment, a number of the partial records to be prefetched is determined by gathering a plurality of descriptor information for a command according to a predetermined algorithm having a plurality of assumptions for the command. The number of partial records is prefetched. At least one of record headers and record keys of the number of partial records are concatenated into the single DMA operation. The DMA operation is forwarded to a receiver process to be completed.

Abstract: Method, system and computer program product embodiments for, in an input/output (I/O) link handling complex instruction chains, a messaging scheme incorporating a method of error recovery between an initiator processor and a receiver processor, are provided. An operation initiation message is been sent from the initiator processor to the receiver processor for the receiver processor to begin work on an operation. If determined to be necessary, a terminate operation message is sent from the initiator processor to the receiver processor. The initiator processor withholds sending additional messages for the operation until a terminate operation response message is received. Once the terminate operation message is received, outstanding messages in process are flushed from the receiver processor. The receiver processor withholds sending additional messages to the initiator processor as the outstanding messages are completed.

Abstract: A method for facilitating input/output (I/O) communication for a processing operation is provided. An interrogate command is obtained by an I/O communications adapter. The interrogate command queries for status information of the processing operation to be provided in an interrogate response. A fixed number of resources and a time allocated to the interrogate command is throttled by pre-allocating the fixed number of resources needed for the interrogate command, and maintaining a timestamp for a interrogate message. The interrogate message is forwarded from the I/O communications adapter to a control unit. If the interrogate response is not received by the I/O communications adapter within a limited timeout period as measured by the timestamp, or if the interrogate message is received while the fixed number of pre-allocated resources are in use, the I/O communications adapter returns a busy response indicating the control unit is busy to prevent overrunning the control unit.

Abstract: A method is disclosed to control access to stored information. The method supplies a control unit in communication with a computing device and in communication with stored information. If the computing device requests access to that stored information, the method determines if access to the stored information is available. When access to the stored information becomes available, then the method reserves a communication pathway interconnecting the control unit and the requesting computing device, thereby disallowing the sending of non-MPLF unsolicited status via that reserved communication pathway, and provides a message to the computing device, using that reserved communication pathway, granting access to the stored information.

Abstract: A method of packaging a plurality of repeating commands for device command word (DCW) processing in a computer environment having an I/O link handling complex instruction chains for a processing operation is provided. Locate record information is packaged into DCW prefix parameter data. The locate record information includes an intent count argument. The plurality of repeating commands are embedded as a truncated concatenation to the first locate record information. The plurality of repeating commands are identified by redefining the intent count argument for the plurality of repeating commands as a repeat count argument using a flag argument incorporated into the locate record information. The repeat count argument indicates a number of times for a control unit in the computer environment to execute the plurality of repeating commands.

Abstract: A method of packaging locate record commands for device command word (DCW) processing is provided. A first locate record command is packaged into DCW prefix parameter data. The first locate record command includes first search and first seek arguments, a first intent count argument, a first transfer length factor argument, and a plurality of remaining arguments. A plurality of truncated locate record commands is embedded in the DCW prefix parameter data as concatenations to the first locate record command. Each of the plurality of truncated locate record commands include a unique search argument, intent count argument, and transfer length factor argument. Seek argument parameters for each of the plurality of truncated locate record commands are calculated by taking an offset from the first seek argument and the first search argument, applying the offset to each of the plurality of truncated locate record commands. The plurality of remaining arguments is shared.