Abstract: A method for scanning a message-list accessible to a plurality of processors includes retrieving, from a cache associated with a scanning processor from the plurality of processors, information identifying a starting message-slot. This information is then used to begin a scan of the message-list at that starting message-slot. The information indicating the starting message-slot is obtained by identifying, in the message-list, a message-slot containing a message intended for a recipient processor from the plurality of processors and obtaining, from the identified message-slot, information indicative of a location of a succeeding message-slot in the message-list. This information is then cached, for retrieval during a subsequent scan of the message-list.

Abstract: A data transfer arrangement transfers data from a source device, such as a local mass storage facility, to a destination device, such as a remote storage facility. The data transfer arrangement comprises a source device and a destination device. The source device transfers to the destination device a data block including data and padding along with a source check value that is a function of the data and selectively the padding, and a check indication indicating whether the check value is the function of the data alone, or the data and the padding. The destination device, after receiving the data block, source check value and check indication, generates a destination check value that is the function of the data alone, or the data and the padding, based on the check indication, and uses the source and destination check values to determine whether the data block was correctly received.

Abstract: This invention is a system and method for improving performance of a backup operation of data from a data storage system to a media library. In response to a computer system request to backup a slot or track of data, a data engine in communication with the system and a data storage system selectively reads the requested data. Such data engine reads may occur concurrent to host access for I/O operations by employing a protection scheme, e.g. a protection bit. Simultaneously, different backup sessions may read the same track of data that has been read by the data engine. The data slot or track remains in cache memory of the data storage system until all protection bits are reset. A requested slot or track may be moved to a sidefile stored in the cache memory if a host requested to write to it while protection bits are still set and then sent to the Data engine for transfer to a media library.

Abstract: This invention is a system and method for efficiently carrying out a restore operation in a data storage environment. The present invention is a system and method for restoring data in a manner that reduces wait time of associated resources. Logic, which is part of the invention, determines whether a restore is in progress when an application on a computer system is involved in trying to perform an I/O operation on a track of data. A protective scheme is used to keep such data from being updated while the restore is taking place. Importantly the system resources do not have to wait for the restore to complete to carry out I/O operations, which are accounted for separately from the data itself and then a synchronization occurs following completion of the restore.

Abstract: Transferring data from a local storage device to a remote storage device includes providing a first portion of data to a cache memory of the local storage device, marking the first portion of data as write pending, and, in response to transferring a second portion of data related to the first portion of data prior to the first portion of data being transferred to the remote storage device, transferring the first and second portions of data from the local storage device to the remote storage device. The data may be transferred using RDF format. The first portion of data may be a first block and the second portion of data may be a second block and the first and second blocks may be part of a same sector of data. Transferring the data may also include setting a wpmode flag in response to the first portion of data not being transferred when a request to transfer the second portion of data is made.

Abstract: Providing data from a volume of a remote storage device coupled to a local storage device that is coupled to a host, includes providing a command to the remote storage device to request the data, if the data is stored in a cache portion of the remote storage device, the remote storage device providing the data, and if the data is not stored in the cache portion of the remote storage device, the remote storage device causing the data to be fetched from the volume and returning one of: a disconnect or an indicator that the data was not found. Causing the data to be fetched from the volume may include creating a separate wait task that waits for the data to be fetched from the volume. The separate wait task may be created only if there is not already another wait task waiting for the same data. The wait task may post an error if the data is not fetched after a predetermined amount of time, such as four seconds.

Abstract: Providing data from a volume of a remote storage device coupled to a local storage device that is coupled to a host, includes providing a command to the remote storage device to request the data, if the data is stored in a cache portion of the remote storage device, the remote storage device providing the data, and if the data is not stored in the cache portion of the remote storage device, the remote storage device causing the data to be fetched from the volume and returning one of: a disconnect or an indicator that the data was not found. Causing the data to be fetched from the volume may include creating a separate wait task that waits for the data to be fetched from the volume. The separate wait task may be created only if there is not already another wait task waiting for the same data. The wait task may post an error if the data is not fetched after a predetermined amount of time, such as four seconds.

Abstract: A system for mirroring source data to two or more mirrors includes first and second processors designated to communicate with first and second remote mirrors, respectively. First and second queues in the system receive requests to mirror source data at first and second mirrors, respectively. Each of the queues is periodically scanned by a processor corresponding to the mirror associated with that queue. A mask provides information indicative of any pending mirror requests for sending the source data to the first and second mirrors.

Abstract: Method and apparatus for copying, transferring, backing up and restoring data are disclosed. The data can be copied, backed up or restored in segments sizes larger than the data blocks which comprise a logical object. In some embodiments, the segment can correspond to a track of a primary storage device and the data blocks to a fixed size block. In some instances, copying, storage and transfer of the segments which include multiple data blocks can result in transfer of a data block not in a logical object.

Abstract: A mechanism to support remote mirroring of storage devices by data storage systems in a one-to-many switched environment. Each data storage system includes a disk director that is adapted to control at least one device group that is supported in a mirrored configuration with a corresponding device group controlled by one of the other data storage systems. For each device group and corresponding device group, there are first ports associated with the device group and second ports associated with the corresponding device group. A switch element is adapted to connect one of the first ports to at least one of the second ports so that data may be exchanged between the ports for each device group and corresponding device group. The disk director selects which first port is to be connected to which second port via the switch element in the establishment of a logical link.

Abstract: Transmitting data from a source to a destination, includes receiving the data from the source and providing the data to the destination using a network, where the data is acknowledged to the source as being successfully received at the destination prior to all of the data being provided to the network. The source may be a primary storage device. The destination may be a secondary storage device. The data may be provided from the source in a first format and may be provided to the network in a second format that is different from the first format where the first format may be RDF and the second format may be TCP/IP or UDP. The destination may receive the data in a first format different from a second format used to transmit the data over the network. The first format may be RDF and the second format may be TCP/IP or UDP.