Abstract: Various embodiments provide systems and methods for migrating data. One system includes a small computer system interface logical unit number (SCSI LUN) configured to store protected data, a processor, and memory configured to store a peer-to-peer remote copy (PPRC) application. The processor is configured to execute the PPRC application to modify the protection in transmitted data and received data. One method includes receiving unprotected data, utilizing a PPRC application to add protection to the data to generate protected data, and storing the protected data in a protected SCSI LUN. Another method includes receiving, at a protected SCSI LUN, a request to transmit protected data, utilizing a PPRC application to strip the protection from the protected data to generate unprotected data, and transmitting the unprotected data to an unprotected SCSI LUN.

Abstract: A method for verifying the integrity of a communication link is disclosed herein. In selected embodiments, such a method may include detecting, during normal operation of a communication link, a condition indicative of a high failure rate (HFR) on the communication link. The method may further include placing the communication link in an HFR state as a result of the condition. While in HFR state, the method may repeatedly transmit test I/Os over the communication link. The method may then automatically exit HFR state and resume normal operation on the communication link when one or more of the following has occurred: a selected number of test I/Os have been successfully transmitted over the communication link, and a number of test I/Os have been successfully transmitted over the communication link for a selected period of time. A corresponding system, apparatus, and computer program product are also disclosed and claimed herein.

Abstract: Provided are a method for selecting a path comprising ports on primary and secondary clusters to use to transmit data at a primary volume to a secondary volume. A request is received to copy data from a primary storage location to a secondary storage location. A determination is made from a plurality of primary clusters of an owner primary cluster for the primary storage location, wherein the primary clusters are configured to access the primary storage location. A determination is made as to whether there is at least one port on the owner primary cluster providing an available path to the secondary storage location. One port on the owner primary cluster is selected to use to copy the data to the secondary storage location in response to determining that there is at least one port on the owner primary cluster available to transmit to the secondary storage location.

Abstract: A method for dynamically enabling and disabling use of XFR_RDY is disclosed herein. In one embodiment of the invention, such a method includes receiving a write command at a target and determining whether XFR_RDY is enabled or disabled for the write command. In the event XFR_RDY is disabled, the method determines whether one or more buffers are available at the target. If at least one buffer is available, the method processes the write command by writing data associated with the write command to the one or more buffers. The method then returns information indicating the number of buffers that are still available at the target after completing the write command. A corresponding apparatus and computer program product are also disclosed and claimed herein.

Abstract: A method for verifying the integrity of a communication link is disclosed herein. In selected embodiments, such a method may include detecting, during normal operation of a communication link, a condition indicative of a high failure rate (HFR) on the communication link. The method may further include placing the communication link in an HFR state as a result of the condition. While in HFR state, the method may repeatedly transmit test I/Os over the communication link. The method may then automatically exit HFR state and resume normal operation on the communication link when one or more of the following has occurred: a selected number of test I/Os have been successfully transmitted over the communication link, and a number of test I/Os have been successfully transmitted over the communication link for a selected period of time. A corresponding system, apparatus, and computer program product are also disclosed and claimed herein.

Abstract: Various embodiments provide systems and methods for migrating data. One system includes a small computer system interface logical unit number (SCSI LUN) configured to store protected data, a processor, and memory configured to store a peer-to-peer remote copy (PPRC) application. The processor is configured to execute the PPRC application to modify the protection in transmitted data and received data. One method includes receiving unprotected data, utilizing a PPRC application to add protection to the data to generate protected data, and storing the protected data in a protected SCSI LUN. Another method includes receiving, at a protected SCSI LUN, a request to transmit protected data, utilizing a PPRC application to strip the protection from the protected data to generate unprotected data, and transmitting the unprotected data to an unprotected SCSI LUN.

Abstract: A method for verifying the integrity of a communication link is disclosed herein. In selected embodiments, such a method may include detecting, during normal operation of a communication link, a condition indicative of a high failure rate (HFR) on the communication link. The method may further include placing the communication link in an HFR state as a result of the condition. While in HFR state, the method may repeatedly transmit test I/Os over the communication link. The method may then automatically exit HFR state and resume normal operation on the communication link when one or more of the following has occurred: a selected number of test I/Os have been successfully transmitted over the communication link, and a number of test I/Os have been successfully transmitted over the communication link for a selected period of time. A corresponding system, apparatus, and computer program product are also disclosed and claimed herein.

Abstract: A method to maintain write operation atomicity where a write operation crosses a data storage medium track boundary. The method supplies a storage controller comprising a host adapter, a processor, and a NVS. The host adapter receives from a host computer a write request and data. The method determines if the write request will cross a data storage medium track boundary. If the write request will cross a data storage medium track boundary, the method indicates to the host adapter that the write request comprises a two-track transfer, and writes the data to the NVS as the data is received. If the host computer fails prior to providing all the data to the storage controller, the method discards the data written to the NVS to ensure write operation atomicity.

Abstract: Provided are a system and article of manufacture for bidirectional data transfer. In certain embodiments a link layer login is sent from a first port to a second port. Subsequently, an application layer login is sent from the first port to the second port to establish a first data path, wherein the first data path is from the first port to the second port. Subsequently, another application layer login is sent from the second port to the first port to establish a second data path, wherein the second data path is from the second port to the first port. In certain other embodiments, a first data path is established from a first port to a second port. A determination is made at the first port, whether the second port has a second data path established from the second port to the first port. An application layer logout is sent from the first port to the second port, in response to determining that the second port has the second data path established from the second port to the first port.

Abstract: A method, system, and computer program product to preserve data integrity in a mirror and copy environment is disclosed herein. In one embodiment, a method may include receiving a write command and data from a host device. The method may further include writing the data to a primary storage device and attaching a primary sequence number associated with the primary storage device to the write command, thereby providing a numbered write command with a command sequence number. The numbered write command may then be transmitted to a secondary storage device. The method may further include comparing the command sequence number to a secondary sequence number associated with the secondary storage device. If the command sequence number matches the secondary sequence number, then the command may be executed. Otherwise, it may be ignored.

Abstract: A method to maintain write operation atomicity where a write operation crosses a data storage medium track boundary. The method supplies a storage controller comprising a host adapter, a processor, and a NVS. The primary host adapter receives from a host computer a write request and data. The method determines if the write request will cross a data storage medium track boundary. If the write request will cross a data storage medium track boundary, the method indicates to the host adapter that the write request comprises a two-track transfer, and writes the data to the primary NVS as the data is received. If the host computer fails prior to providing all the data to the storage controller, the method discards the data written to the NVS to ensure write operation atomicity.

Abstract: A method for performing a data exchange between an initiator and a receiver in a fiber channel protocol (FCP) is provided. A control flag is set in a write command to indicate the presence of an identifier. The identifier is copied into a command descriptor block (CDB) of the write command and appended to a data frame. The write command and data frame, including the identifier, is sent from the initiator to the receiver.

Abstract: Provided are techniques for determining a link speed. When a link between two computing devices is operational, a link speed for use in communicating across the link is stored and a remembered indicator is set to TRUE. After any event occurs that causes the link to become inoperational, in response to determining that the remembered indicator is TRUE, the stored link speed is used when attempting to make the link become operational.

Abstract: A method for performing a data exchange between an initiator and a receiver in a fibre channel protocol (FCP) is provided. A control flag is set in a write command to indicate the presence of an identifier. The identifier is copied into a command descriptor block (CDB) of the write command and appended to a data frame. The write command and data frame, including the identifier, is sent from the initiator to the receiver.

Abstract: A first device determines a possibility of an invalidation of a second device, wherein the first device is coupled to the second device via a fabric. A query is sent from the first device to validate the second device, in response to determining the possibility of the invalidation of the second device. A determination is made, at the first device, whether to continue I/O operations from the first device to the second device based on receiving a response to the query within a time period.

Abstract: Provided are techniques for determining a link speed. When a link between two computing devices is operational, a link speed for use in communicating across the link is stored and a remembered indicator is set to TRUE. After any event occurs that causes the link to become inoperational, in response to determining that the remembered indicator is TRUE, the stored link speed is used when attempting to make the link become operational.

Abstract: Provided are a method, system and article of manufacture for bidirectional data transfer. In certain embodiments a link layer login is sent from a first port to a second port. Subsequently, an application layer login is sent from the first port to the second port to establish a first data path, wherein the first data path is from the first port to the second port. Subsequently, another application layer login is sent from the second port to the first port to establish a second data path, wherein the second data path is from the second port to the first port. In certain other embodiments, a first data path is established from a first port to a second port. A determination is made at the first port, whether the second port has a second data path established from the second port to the first port. An application layer logout is sent from the first port to the second port, in response to determining that the second port has the second data path established from the second port to the first port.

Abstract: Provided are a system and article of manufacture for bidirectional data transfer. In certain embodiments a link layer login is sent from a first port to a second port. Subsequently, an application layer login is sent from the first port to the second port to establish a first data path, wherein the first data path is from the first port to the second port. Subsequently, another application layer login is sent from the second port to the first port to establish a second data path, wherein the second data path is from the second port to the first port. In certain other embodiments, a first data path is established from a first port to a second port. A determination is made at the first port, whether the second port has a second data path established from the second port to the first port. An application layer logout is sent from the first port to the second port, in response to determining that the second port has the second data path established from the second port to the first port.