Showing papers by "Harry M. Yudenfriend published in 2016"

Generating a chain of a plurality of write requests

Abstract: Provided are a computer program product, system, and method for generating a chain of a plurality of write requests including a commit wait flag and plurality of write requests. The commit wait flag is set to one of an indicated first value or a second value. The commit wait flag is set to the first value to cause a storage server to process the write requests by requiring a current write request being processed to complete before transferring data for a next write request following the current write request. The commit wait flag is set to the second value to cause the storage server to process the write requests by transferring data for the next write request before completing the current write request preceding the next write request. The write request chain is sent to the storage server to apply the write requests to the storage.

I/o processing system including dynamic missing interrupt and input/output detection

Abstract: An I/O processing system includes an operating system configured to control an input/output (I/O) device, which executes an I/O operation in the I/O processing system. The I/O processing system further includes a channel subsystem module configured to output an interrogation command signal while the I/O device executes an I/O request. The I/O device returns an I/O status signal indicating a status of an ongoing I/O request, and the operating system is configured to dynamically determine a timeout event of the I/O request based on the status of the ongoing I/O request.

Hardware-assisted protection for synchronous input/output

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.

Management of allocation for alias devices

Abstract: Embodiments of the present invention provide systems, methods, and computer program products for managing computing devices to handle an input/output (I/O) request. In one embodiment, the I/O request may eligible for performance throttling based, at least in part, on the associated importance level for performing the received I/O request and one or more characteristics of the received I/O request. Embodiments of the present invention provide systems, methods, and computer program products for throttling the I/O request and transmitting the I/O request to a storage controller.

Resource allocation for a storage area network

Abstract: Provided are a computer program product, system, and method for resource allocation in accordance with one embodiment of the present description, in which a resource allocation such as a buffer credit allocation for a port in a storage area network is initialized as a function of a measurement of a length of a communication link for the port of the storage area network. In one embodiment, the length measurement is a function of a minimum command response time of a command issued over the communication link. Other aspects of resource allocation in accordance with the present description are described.

Processing a chain of a plurality of write requests

Abstract: Provided are a computer program product, system, and method for processing a chain of a plurality of write requests including a commit wait flag and plurality of write requests, wherein each write request group includes write transactions directed to the storage. A determination is made as to whether the commit wait flag has a first value or a second value. The write requests are processed by requiring a current write request comprising one of the write requests being processed to complete before beginning to write data for a next write request following the current write request in the write request chain in response to the commit wait flag having the first value. The write requests are processed by processing the next write request before completing the current write request in response to the commit wait flag having the second value.

Access control and security for synchronous input/output links

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.

Determining correct devices to use in a mass volume migration environment

Abstract: A computer-implemented method for determining correct devices to use in a mass volume migration environment includes reading an I/O configuration definition for a plurality of devices in the mass volume migration environment and definition of a second set of the plurality of devices, wherein the plurality of devices comprise a first set of the plurality of devices. The method includes executing a migration and annotating the first set and the second set with status identifiers. The method also includes responsive to completing a migration of a device in the first set to the associated corresponding device in the second set, updating the annotation of the migrated device in the first set and the corresponding device in the second set and swapping the migrated device in the first set with the corresponding device in the second set, and continuing the migration of devices of the first set to the second set.

Maintaining cyclic redundancy check context in a synchronous I/O endpoint device cache system

Abstract: A method of maintaining a device table cache (DTC) included in a Synchronous input/output (I/O) computing system includes issuing, with a processor executing an operating system running on the Synchronous I/O computing system, a Synchronous I/O command indicating a request to perform a device table entry transaction including a plurality of device table entries. The method also includes determining, with a host bridge processor, based on device table information, whether the device table entry transaction is associated with a cyclic redundancy check (CRC) transaction, and pinning, with the host bridge processor, a device table entry from a device table based on the determination.

Adjustment of an information unit pacing credit to increase data transmission rate

Abstract: A first device determines whether an indicator is configured to allow use of an increased value for an information unit pacing credit that is greater than a default value for the information unit pacing credit, where the information unit pacing credit indicates a number of information units that a second device is allowed to send to the first device without waiting for any additional response from the first device. In response to determining that the indicator is configured to allow use of the increased value for the information unit pacing credit that is greater than the default value for the information unit pacing credit, the first device adjusts the information unit pacing credit via a response sent from the first device to the second device, to the increased value that is greater than the default value.