Abstract: A computer-implemented method for synchronous input/output (I/O) cache line padding is described. The cache line padding occurs between a server having a processor executing an operating system and a recipient control unit. The method can include receiving, via the processor at the recipient control unit, a partial line direct memory access (DMA) write request; fetching, via the processor, a device table entry (DTE) associated with the partial line DMA write request; determining, via the processor, a cache line size for a synchronous input/output (I/O) cache line; and writing a full cache line DMA write request by padding, via the processor, the partial line DMA write request with a padded portion, where the padded portion is based on the cache line size.

Abstract: A synchronous input/output (I/O) computing system includes a processor and a memory unit that stores program instructions. The system is configured to purge a device table cache (DTC) in response to the processor executing the program instructions. An operating system runs on the synchronous I/O computing system and issues a synchronous I/O command indicating a request to perform a device table entry transaction that has a total data length to be transferred. A device table entry is selected from a device table, loaded into the DTC, and data packets corresponding to the device table entry transaction are transferred using the selected device table entry. A host bridge processor monitors the data packets transferred using the selected table entry, and automatically purges the selected device table entry from the DTC in response to determining the transferred data packets match the total data length.

Abstract: Examples of techniques for hardware assisted data protection are disclosed. In one example implementation according to aspects of the present disclosure, a method may include receiving a read data record comprising at least one memory write, the read data record having an associated cyclic redundancy check (CRC). The method may further include calculating, by a hardware module, an expected CRC for the read data record. Additionally, the method may include comparing the expected CRC to a known CRC stored in a known CRC data store. Finally, the method may include authenticating the read data record when the expected CRC matches a corresponding known CRC.

Abstract: Examples of techniques for hardware assisted data protection are disclosed. In one example implementation according to aspects of the present disclosure, a method may include receiving a read data record comprising at least one memory write, the read data record having an associated cyclic redundancy check (CRC). The method may further include calculating, by a hardware module, an expected CRC for the read data record. Additionally, the method may include comparing the expected CRC to a known CRC stored in a known CRC data store. Finally, the method may include authenticating the read data record when the expected CRC matches a corresponding known CRC.

Abstract: Examples of techniques for hardware assisted data protection are disclosed. In one example implementation according to aspects of the present disclosure, a method may include receiving a read data record comprising at least one memory write, the read data record having an associated cyclic redundancy check (CRC). The method may further include calculating, by a hardware module, an expected CRC for the read data record. Additionally, the method may include comparing the expected CRC to a known CRC stored in a known CRC data store. Finally, the method may include authenticating the read data record when the expected CRC matches a corresponding known CRC.

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: Aspects include communicating synchronous input/output (I/O) commands between a system and a recipient. The system executes on a processor coupled to a memory so as to issue, to the recipient, a synchronous I/O command with a diagnostic operation code, where the synchronous I/O command causes a gathering of diagnostic information by the recipient. Further, the system receives, from the recipient, status information including a diagnostic information identifier, the status information being in accordance with the diagnostic information.

Abstract: Aspects include communicating synchronous input/output (I/O) commands between a system and a recipient. The system executes on a processor coupled to a memory so as to issue, to the recipient, a synchronous I/O command with a diagnostic operation code, where the synchronous I/O command causes a gathering of diagnostic information by the recipient. Further, the system receives, from the recipient, status information including a diagnostic information identifier, the status information being in accordance with the diagnostic information.

Abstract: Aspects include transmitting a synchronous I/O command to a persistent storage control unit (SCU in response to a synchronous I/O request from an operating system (OS). 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. Based on an operation code of the synchronous I/O command specifying a read operation and in response to detecting that the persistent SCU has stored one or more read data records in a memory located on the processor, the firmware indicates to the OS that the synchronous I/O request is completed. Based on the operation code specifying a write operation and in response to detecting an indication from the persistent SCU that write data has been written or indicating that an error has occurred, indicating to the OS that the synchronous I/O request is completed.

Abstract: Aspects include communicating synchronous input/output (I/O) commands between an operating system and a recipient. Communicating synchronous I/O commands includes issuing a first synchronous I/O command with a first initiation bit set, where the first synchronous I/O command cause a first mailbox command to be initiated by the recipient with respect to a first storage control unit. Further, communicating synchronous I/O commands issuing a second synchronous I/O command with a second initiation bit set, where the second synchronous I/O command causes a second mailbox command to be initiated by the recipient with respect to at least one subsequent storage control unit. Communicating synchronous I/O commands also includes issuing a third synchronous I/O command with a first completion bit set in response to the first mailbox command being initiated and issuing a fourth synchronous I/O command with a second completion bit set in response to the first mailbox command being initiated.

Abstract: Aspects include communicating synchronous input/output (I/O) commands between an operating system and a recipient. Communicating synchronous I/O commands includes issuing a first synchronous I/O command with a first initiation bit set, where the first synchronous I/O command cause a first mailbox command to be initiated by the recipient with respect to a first storage control unit. Further, communicating synchronous I/O commands issuing a second synchronous I/O command with a second initiation bit set, where the second synchronous I/O command causes a second mailbox command to be initiated by the recipient with respect to at least one subsequent storage control unit. Communicating synchronous I/O commands also includes issuing a third synchronous I/O command with a first completion bit set in response to the first mailbox command being initiated and issuing a fourth synchronous I/O command with a second completion bit set in response to the first mailbox command being initiated.

Abstract: Aspects include accessing data located on peripheral devices using synchronous input/output (I/O). A unit of work is received by an operating system (OS) executing on a processor. The unit of work includes an I/O request to access data located on a persistent storage control unit (SCU) that is external to the processor. It is determined that the I/O request should be serviced by a synchronous I/O. A synchronous I/O is initiated to the persistent SCU to service the I/O request based on determining that the I/O request should be serviced by a synchronous I/O. The unit of work is kept active while waiting for the synchronous I/O to complete. A notification that the I/O has completed is received and the unit of work is completed in response to receiving the notification.

Abstract: Aspects include accessing data located on peripheral devices using synchronous input/output (I/O). A unit of work is received by an operating system (OS) executing on a processor. The unit of work includes an I/O request to access data located on a persistent storage control unit (SCU) that is external to the processor. It is determined that the I/O request should be serviced by a synchronous I/O. A synchronous I/O is initiated to the persistent SCU to service the I/O request based on determining that the I/O request should be serviced by a synchronous I/O. The unit of work is kept active while waiting for the synchronous I/O to complete. A notification that the I/O has completed is received and the unit of work is completed in response to receiving the notification.

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 transmitting a synchronous I/O command to a persistent storage control unit (SCU in response to a synchronous I/O request from an operating system (OS). 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. Based on an operation code of the synchronous I/O command specifying a read operation and in response to detecting that the persistent SCU has stored one or more read data records in a memory located on the processor, the firmware indicates to the OS that the synchronous I/O request is completed. Based on the operation code specifying a write operation and in response to detecting an indication from the persistent SCU that write data has been written or indicating that an error has occurred, indicating to the OS that the synchronous I/O request is completed.

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 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 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.