Abstract: Provided are a method, system, and program for copying tracks between a primary controller and secondary controller. A track is received from the primary controller that is part of a copy job comprising a sequence of tracks to copy along with a sequence number of the received track and a context number identifying computational resources in the primary controller used to transmit the track, sequence number, and context number. The context number and sequence number transmitted with the track are used to determine if a track preceding the received track was written to storage. The secondary-controller writes the received track to storage if the track preceding the received track was written to storage.

Abstract: Provided are a system and article of manufacture, wherein in certain embodiments an I/O command from a host is received at a first storage unit. An identifier is generated that identifies a destination to which the I/O command is to be transmitted from the first storage unit. The I/O command is augmented with the generated identifier at the first storage unit. The augmented I/O command is transmitted. In certain other embodiments, an I/O command is received at a storage unit, wherein the storage unit is associated with a storage unit identifier. A determination is made at the storage unit, whether the I/O command is associated with an identifier that identifies a destination for which the I/O command is intended. A further determination is made, at the storage unit, whether the identifier is the same as the storage unit identifier, in response to determining that the identifier associated with the I/O command identifies the destination for which the I/O command is intended.

Abstract: Provided is a method, wherein in certain embodiments an I/O command from a host is received at a first storage unit. An identifier is generated that identifies a destination to which the I/O command is to be transmitted from the first storage unit. The I/O command is augmented with the generated identifier at the first storage unit. The augmented I/O command is transmitted. In certain other embodiments, an I/O command is received at a storage unit, wherein the storage unit is associated with a storage unit identifier. A determination is made at the storage unit, whether the I/O command is associated with an identifier that identifies a destination for which the I/O command is intended. A further determination is made, at the storage unit, whether the identifier is the same as the storage unit identifier, in response to determining that the identifier associated with the I/O command identifies the destination for which the I/O command is intended.

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.

Abstract: An apparatus, system, and method are provided for maintaining task prioritization and load balancing of I/O tasks on servers coupled by a plurality of communication channels. The apparatus includes a task controller for maintaining system resources on a failed target channel while resubmitting an unsuccessful task to a different channel. Also, the apparatus includes an upgrade module for upgrading a task prioritization level of a failed I/O task. Additionally, a load module is provided for balancing I/O tasks evenly across the plurality of communication channels according to a prioritization algorithm. The system includes the task controller and a device controller configured to interface with the task controller. The method includes a computer readable medium with computer readable code for selecting a channel, upgrading the prioritization level of a failed task, and maintaining resources on the failed channel while resubmitting the failed I/O task on a different channel.

Abstract: An apparatus, system, and method are disclosed for fastload code update on a communications adapter. The apparatus includes an image load module, a memory initialization module, and an image overlay module. The image load module is configured to load a copy of a new code image in a memory on the communications adapter. The memory also concurrently stores a copy of an old code image used by the communications adapter. The memory initialization module is configured to invoke the new code image to perform a memory initialization operation. The memory initialization module may perform the memory initialization operation concurrently with ongoing I/O requests possibly accepted, but not necessarily processed, by the old code image. The image overlay module is configured to overlay the old code image with the new code image. The fastload code update minimizes the time that the communications adapter is off-line to overlay the old code image with the new code image and reinitialize the communications adapter.

Abstract: Provided are a method, system, and program monitoring paths between a first controller and second controller. A determination is made as to whether one path has been unavailable for a predetermined time period in response to detecting that the path is unavailable. Indication is made that the path is in a first failed state if the path has been unavailable for more than the predetermined time period and indication is made that the path is in a second failed state if the path has not been unavailable for the predetermined time period.

Abstract: A processor is used to evaluate information regarding the number, size, and priority level of data transfer requests sent to a plurality of communication ports. Additional information regarding the number, size, and priority level of data requests received by the communication ports from this and other processors is evaluated as well. This information is applied to a control algorithm that, in turn, determines which of the communication ports will receive subsequent data transfer requests. The behavior of the control algorithm varies based on the current utilization rate of communication port bandwidths, the size of data transfer requests, and the priority level of the these transfer requests.

Abstract: Disclosed is a technique for fault isolation. A first error check is performed on a block of data in storage to determine whether the block of data was corrupted after the block of data was transferred from memory to the storage. When the first error check indicates that the block of data was corrupted, a second error check is performed using the block of data in the memory to determine whether the block of data was corrupted before being transferred from the memory. When the second error check indicates that the block of data was corrupted before being transferred from the memory, it is determined that the block of data was corrupted before being stored in the memory. When the second error check indicates that the block of data was corrupted after being transferred from the memory, it is determined that the block of data was corrupted by at least one of the memory or a formatter that performed the transfer.

Abstract: Disclosed is a technique for throttling data transfer. An amount of resources that are in use is determined. When the amount of resources reaches a high threshold, one or more primary control units are notified to temporarily stop sending data. When the amount of resources reaches a low threshold, each previously notified primary control unit is notified to resume sending data.

Abstract: A method, apparatus and program storage device for automatically presenting status from a host bus adapter until an error is detected is provided. Data is transmitted between the host bus adapter and a host. The host performs data transmission validation and determines whether data transmission was successful. The host bus adapter automatically sends status information when data transmission was successful, else the host bus adapter waits for status type identification from the host for transmission of data.

Abstract: A method is disclosed to transfer information from a first information storage and retrieval system to a second information storage and retrieval system. The method provides a first information storage and retrieval system comprising a first track size and a plurality of first tracks, and a second information storage and retrieval system comprising a second track size and a plurality of second tracks. The method determines if the first track size is greater than the second track size. If the method determines that the first track size is greater than said second track size, then the method sets a ratio (R) equal to the first track size divided by the second track size, provides the (i)th first track from the first information storage and retrieval system to the second information storage and retrieval system, provides (R) second tracks, and maps the (i)th first track onto the (R) second tracks.

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: A method, apparatus and program storage device for automatically presenting status from a host bus adapter until an error is detected is provided. Data is transmitted between the host bus adapter and a host. The host performs data transmission validation and determines whether data transmission was successful. The host bus adapter automatically sends status information when data transmission was successful, else the host bus adapter waits for status type identification from the host for transmission of data.