Abstract: Transferring data elements from a source to a destination includes providing a transmission queue at the source, where data elements in the transmission queue are transferred from the source to the destination, determining an optimal length for the transmission queue, where the optimal queue length is inversely proportional data latency time at the destination, and, if the optimal length is greater than an instantaneous length of the transmission queue, adding data elements to the transmission queue. Adding data elements may include adding a number of elements corresponding to a difference between the optimal length and the instantaneous length of the transmission queue. Determining optimal length may include dividing a constant by the data latency time at the destination. Transferring data elements may also include providing a network between the source and the destination.

Abstract: Described are techniques for processing a data operation. A data operation is received at a data storage system. The data operation requests a modification of data stored in the data storage system. A first address is obtained that represents a starting address of the data operation. A calculation is performed representing a boundary condition of the starting address of the data operation. Based on the calculation, it is determined whether the data operation has a starting address which is properly aligned.

Abstract: A system and method for providing continuous availability of information that is normally transported via a network is provided. The system and method uses a process that is used with each computer in a system to simulate the functionality of a network interface card wherein upon the unavailability of the network, transmission packets containing a unique header are send by one application in the system through the process, which stores the transmission packets in queue, and upon filling of the queue writes filled queue to a send volume contained on a storage system. The storage system then copies the data to a second volume, which can be read by a second application. The first and second volumes can either be remotely dispersed or local to one another.

Abstract: A method for processing a request from a host to write a database record to a target location on a logical device associated with a data-storage system in data communication with the host includes maintaining, at the data storage system, information identifying extents of the logical device that are designated for storage of database records, and, on the basis of the information, determining whether the target location is one on which a database record is permitted to be stored.

Abstract: A system and method for providing continuous availability of information that is normally transported via a network is provided. The system and method uses a process that is used with each computer in a system to simulate the functionality of a network interface card wherein upon the unavailability of the network, transmission packets containing a unique header are send by one application in the system through the process, which stores the transmission packets in queue, and upon filling of the queue writes filled queue to a send volume contained on a storage system. The storage system then copies the data to a second volume, which can be read by a second application. The first and second volumes can either be remotely dispersed or local to one another.

Abstract: A method for storing data includes writing the data to a temporary storage location and buffering a mirror request to copy the data from the temporary storage location to a mirror. Once all the data is present, the validity of the data is determined. If the data is valid, the mirror request is executed. Otherwise, the mirror request is deleted.

Abstract: Described are techniques for processing data requests in connection with an I/O operation. A write data request is sent from a host to a target data storage system. The host performs a data validation, such as a checksum calculation, using the data of the data request. The data request is sent to the target data storage system. The target data storage system may be enabled to perform data validation processing on a per device basis by setting one or more device flag bits for a device. The target data storage system performs data validation processing in accordance with the flag bit settings of a device associated with a data request. A target checksum value using the data received on the target data storage system is determined and compared to the host checksum value in order to determined data validity. Data recovery processing is performed if data corruption is determined.

Abstract: Described are techniques used in dynamically modifying RDF groups. A system call is issued by a host computer system to execute a remote system call on a first data storage system to create, remove, or modify an RDF group between the first data storage system and another data storage system that is remotely connected to the first data storage system in an RDF switched environment. As part of executing the remote system call, data is pushed from the first to the second data storage systems without having an established link between the data storage systems. Each data storage system performs processing to make the necessary modifications in all directors in accordance with the dynamic RDF group. A status indicating success or failure of the remote system call is returned to the host computer system.

Abstract: Setting a plurality of table entries in a storage device includes subdividing the table entries into a N tasks, placing each of the N tasks in a memory location disposed within the storage device and accessible by a plurality of internal devices, the plurality of the internal devices accessing the memory location to retrieve at least one of the N tasks, and each of the plurality of the internal devices setting table entries corresponding to at least one of the N tasks retrieved from the memory location. Setting table entries may also include setting logical device table entries to indicate corresponding tracks contain invalid data in connection with operation of remote data transfer between multiple storage devices.

Abstract: Described are techniques used in detection of a data corruption in a computer system. A host issues a write request that includes a checksum value determined in accordance with data associated with the write request. The write request is received by a data storage system that performs data validation using the checksum. If the data validation succeeds, the write operation proceeds. Otherwise, it is determined that the data is corrupt and a checksum error is returned to the issuing host. The host issues a vendor-defined write request operation that includes the checksum as a data field in the request packet sent to the data storage system. Filter drivers are used in obtaining the checksum and modifying the write request packet to specify a vendor-defined write operation if checksumming is enabled for the write operation.

Abstract: Described are techniques used in dynamically modifying RDF groups. A system call is issued by a host computer system to execute a remote system call on a first data storage system to create, remove, or modify an RDF group between the first data storage system and another data storage system that is remotely connected to the first data storage system in an RDF switched environment. As part of executing the remote system call, data is pushed from the first to the second data storage systems without having an established link between the data storage systems. Each data storage system performs processing to make the necessary modifications in all directors in accordance with the dynamic RDF group. A status indicating success or failure of the remote system call is returned to the host computer system.

Abstract: Setting a plurality of table entries in a storage device includes subdividing the table entries into a N tasks, placing each of the N tasks in a memory location disposed within the storage device and accessible by a plurality of internal devices, the plurality of the internal devices accessing the memory location to retrieve at least one of the N tasks, and each of the plurality of the internal devices setting table entries corresponding to at least one of the N tasks retrieved from the memory location. Setting table entries may also include setting logical device table entries to indicate corresponding tracks contain invalid data in connection with operation of remote data transfer between multiple storage devices. At least some of the internal devices may include devices for handling remote data transfer between multiple storage devices. At least some of the internal devices may be disk adapters and host adapters of the storage device. The memory location may correspond to a queue.

Abstract: Setting a plurality of table entries in a storage device includes subdividing the table entries into a N tasks, placing each of the N tasks in a memory location disposed within the storage device and accessible by a plurality of internal devices, the plurality of the internal devices accessing the memory location to retrieve at least one of the N tasks, and each of the plurality of the internal devices setting table entries corresponding to at least one of the N tasks retrieved from the memory location. Setting table entries may also include setting logical device table entries to indicate corresponding tracks contain invalid data in connection with operation of remote data transfer between multiple storage devices.

Abstract: Described are techniques used in dynamically modifying RDF groups. A system call is issued by a host computer system to execute a remote system call on a first data storage system to create, remove, or modify an RDF group between the first data storage system and another data storage system that is remotely connected to the first data storage system in an RDF switched environment. As part of executing the remote system call, data is pushed from the first to the second data storage systems without having an established link between the data storage systems. Each data storage system performs processing to make the necessary modifications in all directors in accordance with the dynamic RDF group. A status indicating success or failure of the remote system call is returned to the host computer system.

Abstract: A method and apparatus for enabling an on-line reconfiguration of striped data in a disk array storage device. A replicated copy of the striped logical device is made in parallel with host operations. A logical device with a new configuration is then substituted for access by the host application even before any data is transferred to locations within the newly configured logical device. Independent processes operating in this disk array storage device reconfigure the data transparently to any host operations while accommodating host I/O requests directed to locations in the new configuration.

Abstract: Disk array storage device apparatus for enhancing the performance of an application on a data processing system that operates with a disk array storage device in which the completion of tasks associated with different transactions with one logical storage device are conditions precedent to the completion of other transactions. Specific tasks related to the one logical device are given priority over tasks related to all other logical storage devices. In a specific implementation reconnect tasks are given the highest priority with reconnect tasks from the one logical storage device being given the highest priority. A second category of tasks related to the one logical storage device can be given priority over all other tasks except reconnect tasks. All other tasks are given a priority below that of the first and second task categories.

Abstract: A method and apparatus for enabling an on-line reconfiguration of striped data in a disk array storage device. A replicated copy of the striped logical device is made in parallel with host operations. A logical device with a new configuration is then substituted for access by the host application even before any data is transferred to locations within the newly configured logical device. Independent processes operating in this disk array storage device reconfigure the data transparently to any host operations while accommodating host I/O requests directed to locations in the new configuration.

Abstract: This invention is configured to create and use a special data structure containing a data storage device's identification information for a storage device that will be duplicated. Upon such duplication, the special data is stored in a predetermined location on another device receiving the copied data and a flag bit is set to indicate whether or not the information in the data structure should be used to respond to a host inquiry regarding the identification of the storage device. Without reconfiguring the host's operating software, the system employs a method to respond to and satisfy a host inquiry for the storage device's identification information by employing the special data structure. This is done to avoid host conflict errors that might result from a conflict between identification information being replicated from the storage device and the other storage device to where its data is copied.

Abstract: A method for enhancing the performance of an application on a data processing system that operates with a disk array storage device in which tasks associated with different transactions with one logical storage device are conditions precedent to the completion of other transactions. Specific tasks related to the one logical device are given priority over tasks related to all other logical storage devices. In a specific implementation reconnect tasks are given the highest priority with reconnect tasks from the one logical storage device being given the highest priority. A second category of tasks related to the one logical storage device can be given priority over all other tasks except reconnect tasks. All other tasks are given a priority below that of the first and second task categories.

Abstract: A method and apparatus for enabling an on-line reconfiguration of striped data in a disk array storage device. A replicated copy of the striped logical device is made in parallel with host operations. A logical device with a new configuration is then substituted for access by the host application even before any data is transferred to locations within the newly configured logical device. Independent processes operating in this disk array storage device reconfigure the data transparently to any host operations while accommodating host I/O requests directed to locations in the new configuration.