Abstract: Aspects include for performing an initialization sequence by a first device to execute synchronous input/output (I/O) commands across a synchronous I/O link. The initialization sequence includes posting, by the first device, a first acknowledgement in response to a register area corresponding to a second device being updated with first information according to a first synchronization sequence, the first information comprising a worldwide node name of the second device and posting, by the first device, a second acknowledgement in response the register area being updated with second information according to a second synchronization sequence, the second information comprising mailbox information. The initialization sequence also includes performing, by the first device, a third synchronization sequence to provide a worldwide node name of the first device; and performing, by the first device, a fourth synchronization sequence to provide a status area address.

Abstract: Embodiments of the present invention provide systems and methods for clearing specified blocks of main storage. In one embodiment, an EADM start subchannel is executed. The instructions of the execution of the EADM start subchannel may include a SAP receiving an ADM request block, which specifies a main-storage-clearing operation command. The address and size of a block of main memory to be cleared by the SAP is specified in an MSB designated by the ADM request block.

Abstract: Technical solutions are described for executing a plurality of computer-executable synchronous input/output (I/O) commands received by a storage control unit in a multiple virtual storage system. An example method includes receiving a set of synchronous I/O commands, each of the commands received from a respective operating system from a plurality of operating systems. The method further includes selecting, from the set of synchronous I/O operations, a subset of synchronous I/O commands, and allocating a shared resource to the subset of synchronous I/O commands. The method further includes executing each synchronous I/O command from the selected subset of synchronous I/O commands concurrently.

Abstract: Technical solutions are described for executing a plurality of computer-executable synchronous input/output (I/O) commands received by a storage control unit in a multiple virtual storage system. An example method includes receiving a set of synchronous I/O commands, each of the commands received from a respective operating system from a plurality of operating systems. The method further includes selecting, from the set of synchronous I/O operations, a subset of synchronous I/O commands, and allocating a shared resource to the subset of synchronous I/O commands. The method further includes executing each synchronous I/O command from the selected subset of synchronous I/O commands concurrently.

Abstract: Embodiments of the present invention provide systems and methods for clearing specified blocks of main storage. In one embodiment, an EADM start subchannel is executed. The instructions of the execution of the EADM start subchannel may include a SAP receiving an ADM request block, which specifies a main-storage-clearing operation command. The address and size of a block of main memory to be cleared by the SAP is specified in an MSB designated by the ADM request block.

Abstract: Embodiments of the present invention provide systems and methods for clearing specified blocks of main storage. In one embodiment, an EADM start subchannel is executed. The instructions of the execution of the EADM start subchannel may include a SAP receiving an ADM request block, which specifies a main-storage-clearing operation command. The address and size of a block of main memory to be cleared by the SAP is specified in an MSB designated by the ADM request block.

Abstract: Technical solutions are described for executing a plurality of computer-executable synchronous input/output (I/O) commands received by a storage control unit in a multiple virtual storage system. An example method includes receiving a set of synchronous I/O commands, each of the commands received from a respective operating system from a plurality of operating systems. The method further includes selecting, from the set of synchronous I/O operations, a subset of synchronous I/O commands, and allocating a shared resource to the subset of synchronous I/O commands. The method further includes executing each synchronous I/O command from the selected subset of synchronous I/O commands concurrently.

Abstract: Embodiments of the present invention provide systems and methods for clearing specified blocks of main storage. In one embodiment, an EADM start subchannel is executed. The instructions of the execution of the EADM start subchannel may include a SAP receiving an ADM request block, which specifies a main-storage-clearing operation command. The address and size of a block of main memory to be cleared by the SAP is specified in an MSB designated by the ADM request block.

Abstract: Aspects include communicating synchronous input/output (I/O) commands between an operating system and recipient by issuing a first synchronous I/O command with an initiation bit set, identifying that a mailbox command has been initiated to return control to an operating system before waiting for operations of the first synchronous I/O command to complete, and issuing a second synchronous I/O command with a completion bit set in response to the control returning to the operating system.

Abstract: Aspects include communicating synchronous input/output (I/O) commands between an operating system and recipient by issuing a first synchronous I/O command with an initiation bit set, identifying that a mailbox command has been initiated to return control to an operating system before waiting for operations of the first synchronous I/O command to complete, and issuing a second synchronous I/O command with a completion bit set in response to the control returning to the operating system.

Abstract: Aspects include receiving, at an operating system (OS) executing on a server, a notification that an error was detected during execution of a synchronous I/O operation issued by the OS to a persistent storage control unit (SCU). The notification is received from firmware executing on the server and it includes a command response block that includes error condition information about the error. The method can also include selecting, by the OS, a recovery operation for the synchronous I/O operation. The selecting is based on the error condition information about the error in the command response block. The selected recovery option is performed by the OS.

Abstract: Aspects include receiving, at an operating system (OS) executing on a server, a notification that an error was detected during execution of a synchronous I/O operation issued by the OS to a persistent storage control unit (SCU). The notification is received from firmware executing on the server and it includes a command response block that includes error condition information about the error. The method can also include selecting, by the OS, a recovery operation for the synchronous I/O operation. The selecting is based on the error condition information about the error in the command response block. The selected recovery option is performed by the OS.

Abstract: Aspects include receiving, at an operating system (OS) executing on a server, a notification that an error was detected during execution of a synchronous I/O operation issued by the OS to a persistent storage control unit (SCU). The notification is received from firmware executing on the server and it includes a command response block that includes error condition information about the error. The method can also include selecting, by the OS, a recovery operation for the synchronous I/O operation. The selecting is based on the error condition information about the error in the command response block. The selected recovery option is performed by the OS.

Abstract: Aspects include for performing an initialization sequence by a first device to execute synchronous input/output (I/O) commands across a synchronous I/O link. The initialization sequence includes posting, by the first device, a first acknowledgement in response to a register area corresponding to a second device being updated with first information according to a first synchronization sequence, the first information comprising a worldwide node name of the second device and posting, by the first device, a second acknowledgement in response the register area being updated with second information according to a second synchronization sequence, the second information comprising mailbox information. The initialization sequence also includes performing, by the first device, a third synchronization sequence to provide a worldwide node name of the first device; and performing, by the first device, a fourth synchronization sequence to provide a status area address.

Abstract: Aspects include communicating synchronous input/output (I/O) commands between an operating system and recipient by issuing a first synchronous I/O command with an initiation bit set, identifying that a mailbox command has been initiated to return control to an operating system before waiting for operations of the first synchronous I/O command to complete, and issuing a second synchronous I/O command with a completion bit set in response to the control returning to the operating system.

Abstract: Aspects include communicating synchronous input/output (I/O) commands between an operating system and recipient by issuing a first synchronous I/O command with an initiation bit set, identifying that a mailbox command has been initiated to return control to an operating system before waiting for operations of the first synchronous I/O command to complete, and issuing a second synchronous I/O command with a completion bit set in response to the control returning to the operating system.

Abstract: Aspects include acquiring measurement data of a synchronous input/output (I/O) link between an operating system and a recipient. The acquiring measurement data can include monitoring operating system usage of synchronous I/O commands on the synchronous I/O link and storing the operating system usage in a measurement block as the measurement data. Further, the measurement block is accessible by the operating system to determine that the measurement data is acquired.

Abstract: Aspects include sending a request to perform a unit of work that includes a synchronous I/O operation. The sending is from an operating system (OS) executing on a server to firmware located on the server. The synchronous I/O request includes a command request block that includes an operation code identifying the synchronous I/O operation and a identifier of a persistent storage control unit (SCU). The OS waits for the synchronous I/O to complete and the unit of work remains active during the waiting. The firmware detects that the synchronous I/O operation has completed. A command response block that includes completion status information about the synchronous I/O operation is received by the OS from the firmware. The unit of work is completed in response to the I/O operation completing.

Abstract: Aspects include synchronous input/output (I/O) replication of data. A synchronous I/O request is received from an operating system (OS) by firmware on a server. A plurality of synchronous I/O mailbox commands is transmitted by the firmware to a plurality of persistent storage control unit (SCU) nodes. The content of each of the plurality of synchronous I/O commands is based on the synchronous I/O request. A unit of work in the OS corresponding to the synchronous I/O request remains active at least until the synchronous I/O request is completed. It is determined, by the firmware, that determining that each of the plurality of persistent SCU nodes have completed their respective synchronous I/O commands. Based on the determining, the firmware indicates to the OS that the synchronous I/O request is completed.

Abstract: Aspects include providing automatic access control and security for a synchronous input/output (I/O) link. Providing automatic access control and security includes initializing devices of a storage environment over a first link to verify that the devices are available within the storage environment; building a table of identifiers, where each of the identifiers is assigned one of the devices that have been initialized; and verifying a first device attempting to perform synchronous I/O commands across the synchronization I/O link by confirming that an identifier assigned to the first device is within the table of identifiers.