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: An apparatus, system, and method are disclosed for storing and retrieving compressed data. A compression module compresses a data file organized in logical tracks. A ratio module determines a track compression ratio. The track compression ratio is a ratio of an integer value n to one. A destage module destages a single directory entry for the data file to a directory. The directory entry points to a zeroth track on a hard disk drive. The destage module further destages the data file sequentially to tracks of the hard disk drive from the zeroth track with n logical tracks of the data file stored on one physical track of the hard disk drive. A stage module stages a kth logical track from a physical track of the hard disk drive. The physical track is specified by an integer value of k divided by n.

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, apparatus and program storage device for providing asynchronous status messaging in a data storage system Asynchronous events are returned from a target to an initiator in response to a Read Message from the initiator. The return status message may or may not be associated with a previously given command or Logical Unit (LUN).

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: Disclosed is a technique for assigning priorities. A request to manipulate data is received. A type of the request is determined. A priority is assigned to the request based on the type of the request.

Abstract: An apparatus, system, and method are disclosed for storing and retrieving compressed data. A compression module compresses a data file organized in logical tracks. A ratio module determines a track compression ratio. The track compression ratio is a ratio of an integer value n to one. A destage module destages a single directory entry for the data file to a directory. The directory entry points to a zeroth track on a hard disk drive. The destage module further destages the data file sequentially to tracks of the hard disk drive from the zeroth track with n logical tracks of the data file stored on one physical track of the hard disk drive. A stage module stages a kth logical track from a physical track of the hard disk drive. The physical track is specified by an integer value of k divided by n.

Abstract: Provided are a method for 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: 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: 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 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: A method, apparatus and program storage device for providing asynchronous status messaging in a data storage system Asynchronous events are returned from a target to an initiator in response to a Read Message from the initiator. The return status message may or may not be associated with a previously given command or Logical Unit (LUN).

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 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: 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 providing asynchronous status messaging in a data storage system Asynchronous events are returned from a target to an initiator in response to a Read Message from the initiator. The return status message may or may not be associated with a previously given command or Logical Unit (LUN).