Abstract: A method and apparatus for data recovery in a system involving a first data store acting as a standard device and a physical moving mirror data store that operates as moving mirror with a first mode to be synchronized and in a second, isolated mode. In response to a command to establish a third or protected restore operating mode, the data to be transferred in response to that command is identified. A restoration procedure copies data from the second data store to the first store to recover any data that may have been corrupted in the second data store. An update procedure acts on the restored data concurrently with the restoration procedure.

Abstract: Described are techniques for performing multi-sequential I/O operations in connection with data requests involving a data storage device. An single data request may involve more than a one portion of data associated with a single job record, such as a single request may involve more than a single track of data of a logical device. A single job record corresponds to a single track. A data structure arrangement is disclosed that includes multiple job records corresponding to the single data request involving more than a single track of data. The multiple job records for a single data request are connected together in a data structure arrangement that may be used in connection with a single read operation involving more than a single track of data.

Abstract: Accessing data includes a host establishing a relationship between a first storage area of a first type containing data and a second storage area of a second type containing pointers to data provided in storage areas of the first type, where the storage areas are provided in a storage device coupled to the host. In response to the host writing data to a particular section of the first storage area after establishing the relationship, the particular section is copied from the first storage area to a third storage area of the first type prior to the write operation being executed. A corresponding pointer of the second storage area is adjusted to point to the third storage area.

Abstract: Establishing a plurality of storage areas includes associating each of a first plurality of storage areas of a first type that contain sections of data with corresponding ones of second plurality of storage areas of a second type having pointers to alternative sections of data storage areas of the first type, where initially none of the second plurality of storage areas is available for accessing data corresponding thereto, and, after associating all of the first and second plurality of storage areas, activating the second plurality of storage areas to make the second plurality of storage areas available for accessing data. Exclusive access may be enabled for all of the first plurality of storage areas prior to activating the second plurality of storage areas or to each storage area one at a time.

Abstract: Handling data includes providing a first storage area of a first type that contains sections of data, providing a second storage area of the first type that contains sections of data, providing a third storage area of a second type where the second type has, for each section thereof, a pointer to one of: a corresponding section of data of the first storage area and a corresponding section of data of the second storage area, causing the third storage area to be not available for accessing, and after causing the third storage area to not be available for accessing, providing data from the second storage area corresponding to pointers of the third storage area that point to sections of the second storage area.

Abstract: Accessing stored data includes providing a virtual storage area having a table of pointers that point to sections of at least two other storage areas, where the virtual storage area contains no sections of data, in response to a request for accessing data of the virtual storage area, determining which particular one of the other storage areas contain the data, and accessing the data on the particular one of the other storage areas using the table of pointers. Accessing stored data may also include associating a first one of the other storage areas with the virtual storage area, where the virtual area device represents a copy of data of the first one of the other storage areas. Accessing stored data may also include causing all of the pointers of the table to initially point to sections of the first one of the other storage areas when the virtual storage area is initially associated with the first one of the other storage areas. The storage areas may be storage devices. The sections may be tracks.

Abstract: Restoring data includes providing data in a first storage area that contains sections of data, providing data in a second storage area where the second type has, for each section of data thereof, at least one of: a pointer to a corresponding section of data of the first storage area and a pointer to corresponding section of data of a third storage area of the first type. In one embodiment, a sections of the first storage area are replaced with pointers to the third storage area. In other embodiments, sections of a fourth storage area of the first type are replaced with pointers to the third storage area and optionally with pointers to the first storage area. In another embodiment, data is copied from the second storage area to a third storage area of the second type.

Abstract: A digital data storage system in the form of a mass storage subsystem in which information is stored on one or more disk storage units, with a storage element constituting a track on a disk storage device and each track storing a plurality of records. Each track in each disk storage device of the digital data storage system is associated with a descriptor. When the control device retrieves the contents of a record, it can process the contents to generate a check value and compare the generated check value with the check value for the record as stored in the descriptor associated with the track. If they compare appropriately, the control device can determine that the record that was retrieved was, in fact, the record that was to be retrieved. On the other hand, if they do not compare appropriately, the control device can determine that the record that was retrieved was not the proper record.

Abstract: A digital data storage system comprises a storage device, a descriptor memory and a control device. The storage device stores a series of records, the records being organized in a plurality of tracks, each track being associated with one of a plurality of cylinders. The descriptor memory stores a descriptor associated with storage device. The descriptor contains selected information relating to the records stored by the at least one storage device. Each descriptor includes a plurality of cylinder portions each configured to store selected information relating to a respective one of the cylinders in the storage device. Each cylinder portion, in turn, includes a plurality of track descriptors each configured to store selected information relating to a respective one of the tracks in the respective cylinder. The storage device also stores the descriptor associated therewith, the cylinder portions of the descriptor being augmented with additional information relating to the respective ones of the cylinders.

Abstract: A system and method for initializing large portions, or extents, of a mass-storage device in the background so that such overwriting processes do not significantly affect latency as experienced by a host. The method extends the use a system intended for background copying of data from a source extent to a destination extent to that of initializing an extent on a mass-storage device. It does so by causing the system to treat the defined extent as both a source extent and as a destination extent simultaneously.

Abstract: A method and apparatus for enabling a common data set to be utilized by multiple data processes. During a first operating mode, first and second data stores in a data storage facility with a common buffer attach to a first data process and act as mirrors. Data to be written transfers to the common buffer and then to the data stores. A second command produces a split whereby the first data store remains attached to the first data process and the second data store is available to the second data process. After the second command is executed, any data in the common buffer is transferred to the corresponding data stores in parallel with and transparently to the actions between the first and second data processes and the first and second data stores, respectively.

Abstract: A storage system has a storage controller connected to a plurality of storage devices. The described system and method transfer physical data from a first storage device to a second storage device. The method does not involve a host computer in the physical data transfer thereby saving both computer CPU time and system bandwidth. The method receives an internal copy command from a commanding processor (the host) over a controller input path, reads at least one block of data, in data block format, from the first storage device, stores the requested data in a volatile memory in the controller, and sets a state of the pending stored data as a write pending state. The controller then destages the write pending memory stored data to the second storage device.

Abstract: A data storage system and data storage method providing data storage devices including a data integrity value generator, for allowing individual data storage devices to compute data integrity values in a decentralized manner. A data storage system includes at least one data storage device having a data integrity value generator. A data integrity value generator is responsive to at least first and second data elements, for calculating a data integrity value. In the preferred embodiment, the first and second data elements utilized by the data integrity value generator of a data storage device includes new data received from a data source and old data stored at a predetermined data storage location on the data storage device.

Abstract: A storage system has a storage controller connected to a plurality of storage devices. The described system and method transfer physical data from a first storage device to a second storage device. The method does not involve a host computer in the physical data transfer thereby saving both computer CPU time and system bandwidth. The method receives an internal copy command from a commanding processor (the host) over a controller input path, reads at least one block of data, in data block format, from the first storage device, stores the requested data in a volatile memory in the controller, and sets a state of the pending stored data as a write pending state. The controller then destages the write pending memory stored data to the second storage device.

Abstract: A method and apparatus for enabling a common data set to be utilized by multiple data processes. During a first operating mode, first and second data stores in a data storage facility with a common buffer attach to a first data process and act as mirrors. Data to be written transfers to the common buffer and then to the data stores. A second command produces a split whereby the first data store remains attached to the first data process and the second data store is available to the second data process. After the second command is executed, any data in the common buffer is transferred to the corresponding data stores in parallel with and transparently to the actions between the first and second data processes and the first and second data stores, respectively.

Abstract: A storage system has a storage controller connected to a plurality of storage devices. The described system and method transfer physical data from a first storage device to a second storage device. The method does not involve a host computer in the physical data transfer thereby saving both computer CPU time and system bandwidth. The method receives an internal copy command from a commanding processor (the host) over a controller input path, reads at least one block of data, in data block format, from the first storage device, stores the requested data in a volatile memory in the controller, and sets a state of the pending stored data as a write pending state. The controller then destages the write pending memory stored data to the second storage device.

Abstract: A method and apparatus for enabling a common data set to be utilized by multiple data processes. During a first operating mode, first and second data stores in a data storage facility with a common buffer attach to a first data process and act as mirrors. Data to be written transfers to the common buffer and then to the data stores. A second command produces a split whereby the first data store remains attached to the first data process and the second data store is available to the second data process. After the second command is executed, any data in the common buffer is transferred to the corresponding data stores in parallel with and transparently to the actions between the first and second data processes and the first and second data stores, respectively.

Abstract: A digital data storage system comprising a mass storage subsystem in which information is stored on one or more disk storage units, with a storage element constituting a track on a disk storage device and each track storing a plurality of records. Each track in each disk storage device of the digital data storage system is associated with a descriptor. In that embodiment, when the control device retrieves the contents of a record, it can use the format definition type identifier of the descriptor associated with the track to determine the format definition type for the track, use the specific format information to determine the location and size of the record on the track, and retrieve the record.

Abstract: Two data storage systems are interconnected by a data link for remote mirroring of data. Each volume of data is configured as local, primary in a remotely mirrored volume pair, or secondary in a remotely mirrored volume pair. Normally, a host computer directly accesses either a local or a primary volume, and data written to a primary volume is automatically sent over the link to a corresponding secondary volume. Each remotely mirrored volume pair can operate in a selected synchronization mode including synchronous, semi-synchronous, adaptive copy--remote write pending, and adaptive copy--disk. Each write request transmitted over the link between the data storage systems includes not only the data for at least one track in the secondary volume to be updated but also the current "invalid track" count for the secondary volume as computed by the data storage system containing the corresponding primary volume.

Abstract: A cache management system and method monitors and controls the contents of cache memory coupled to at least one longer term data storage device. Cache memory is organized into at least first and second sections, the first section for storing data waiting to be written to a longer term data storage device and the second section for storing data elements which have been written to the longer term data storage device. The cache management system and method monitors data elements awaiting writing to the longer term data storage device.