Abstract: An automated data storage library stores logical volumes, including logical volumes to be copied to a second library, in cache storage, and migrates logical volumes to physical media volumes stored on storage shelves. In response to a request for recalling one of the logical volumes to be copied to cache, a library controller first determines which physical media volume contains the requested migrated logical volume. The library controller identifies all of the logical volumes to be copied that are migrated and stored as stacked logical volumes on the physical media volume containing the requested migrated logical volume; selects up to “N” of the identified logical volumes, including the requested migrated logical volume; and may arrange a selection list of the selected logical volumes in a sequence in accordance with the order that the logical volumes are written on the physical media volume.

Abstract: Disclosed is a system, method, and an article of manufacture for preferentially keeping an uncopied data set in one of two storage devices in a peer-to-peer environment when data needs to be removed from the storage devices. Each time a data set is modified or newly created, flags are used to denote whether the data set needs to be copied from one storage device to the other. The preferred embodiments modify the timestamp for each uncopied data set by adding a period of time, and thus give preference to the uncopied data set when the data from the storage device is removed based on the least recently used as denoted by timestamp of each data set. Once the data set is copied, the timestamp is set back to normal by subtracting the same period of time added on when the data set was flagged as needing to be copied.

Abstract: A portion of digital data records are stored on a direct access storage device (DASD) in emulation of sequential-access media when the parent digital data records are transferred to a sequential-access media. The efficiency of storage and access to the data portion is improved by random-access recall of the data in the data portion, and by constructing a data portion trailer containing various statistics about the records for referencing the digital data and advancing to target data. The volume data portion trailer is constructed as read forward and forward space block operations are performed. Data is preferably stored in logically assembled records. Interspersed with the records, there may be one or more marker codes, which function like tape marks among the various data records. The volume trailer may contain pointers to each record, a record count and marker codes for the data portion. Statistics contained in the data portion trailer enable substantially more efficient access of the data by a DASD.

Abstract: A method of handling eject requests of logical volumes received by a data storage subsystem from a host system. The method, implemented in computer readable program code, first places identified logical volumes in scratch categories. An eject request is received from a host system, to eject a logical volume from the data storage subsystem. The method responds to the eject request to determine whether the requested logical volume is in a scratch category; if the requested logical volume is determined as to be in a scratch category, a virtual media server is notified that the requested logical volume is deletable, and the virtual media server determines from its database whether the status of the requested logical volume allows deletion thereof. If the virtual media server status determining step allows deletion of the requested logical volume, the requested logical volume is deleted from both the virtual media server database and the library manager database.

Abstract: A portion of digital data records are stored on a direct access storage device (DASD) in emulation of sequential-access media when the parent digital data records are transferred to a sequential-access media. The efficiency of storage and access to the data portion is improved by random-access recall of the data in the data portion, and by constructing a data portion trailer containing various statistics about the records for referencing the digital data and advancing to target data. The volume data portion trailer is constructed as read forward and forward space block operations are performed. Data is preferably stored in logically assembled records. Interspersed with the records, there may be one or more marker codes, which function like tape marks among the various data records. The volume trailer may contain pointers to each record, a record count and marker codes for the data portion. Statistics contained in the data portion trailer enable substantially more efficient access of the data by a DASD.

Abstract: A portion of digital data records are stored on a direct access storage device (DASD) in emulation of sequential-access media when the parent digital data records are transferred to a sequential-access media. The efficiency of storage and access to the data portion is improved by random-access recall of the data in the data portion, and by constructing a data portion trailer containing various statistics about the records for referencing the digital data and advancing to target data. The volume data portion trailer is constructed as read forward and forward space block operations are performed. Data is preferably stored in logically assembled records. Interspersed with the records, there may be one or more marker codes, which function like tape marks among the various data records. The volume trailer may contain pointers to each record, a record count and marker codes for the data portion. Statistics contained in the data portion trailer enable substantially more efficient access of the data by a DASD.

Abstract: A method, apparatus and frame format for allowing the conclusive determination of whether the devices are connected correctly is disclosed. The invention sends a first configuration message to a library manager from a device, the first configuration message including a device address and a serial number associated with the device address, forwards to a control unit from a library manager a second configuration message, the second configuration message including position information for the device and a serial number associated with the device, forwards to the control unit from the device a third configuration message, the third configuration message including position information for the device and a serial number associated with the device and compares at the control unit the second and third configuration messages to determine whether the device and the library manager are configured correctly.

Abstract: A portion of digital data records are stored on a direct access storage device (DASD) in emulation of sequential-access media when the parent digital data records are transferred to a sequential-access media. The efficiency of storage and access to the data portion is improved by random-access recall of the data in the data portion, and by constructing a data portion trailer containing various statistics about the records for referencing the digital data and advancing to target data. The volume data portion trailer is constructed as read forward and forward space block operations are performed. Data is preferably stored in logically assembled records. Interspersed with the records, there may be one or more marker codes, which function like tape marks among the various data records. The volume trailer may contain pointers to each record, a record count and marker codes for the data portion. Statistics contained in the data portion trailer enable substantially more efficient access of the data by a DASD.

Abstract: A virtual data storage system provides a method and apparatus for premigrating host-originated data files initially stored in a cache storage to selected storage volumes within a storage subsystem. A premigration list includes an entry for each cache data file eligible to be premigrated, or copied, to the storage subsystem. Each entry includes a data file identifier, a cache storage location, and a premigration delay criterion. The purpose of the premigration delay criterion is to ensure that the data files are written to the storage subsystem in a timely manner, but to also allow the host processing system to subsequently re-access data files written to the virtual data storage system without interference and delay from the premigration process. The cache data files are not premigrated until the corresponding premigration delay criterion has elapsed, or exceeded a predetermined threshold.

Abstract: A data storage system provides a method and apparatus for preserving consistency between a database back-up and a set of storage volumes. The system includes a storage manager, or storage controller, interconnected to a plurality of storage volumes, a drive, and a database storage. The storage manager receives data files from an attached data processing unit. The storage manager directs the data files such that the files are written to a selected storage volume loaded into the drive. The storage manager maintains reference information and storage volume location information for each data file in the database storage. The storage manager detects a volume full condition when the storage media approaches a predetermined position prior to the physical end of the volume. The storage manager generates a back-up copy of the current database, transfers the database back-up to the drive, and directs the drive to write the database back-up onto the selected storage volume.

Abstract: A virtual data storage system provides a method and apparatus for adaptively throttling transfers into a cache storage to prevent an overrun in the cache storage. The virtual data storage system includes a storage interface appearing as a set of addressable, virtual storage devices, a cache storage for initially storing host-originated data files, storage devices for eventually storing the data files on a set of storage volumes, and a storage manager for directing the data files between the cache storage and the storage devices. An amount of available space in the cache storage, or a cache free space, is monitored against an adjustable cache space threshold. A storage throttle is computed when the cache free space drops below the cache space threshold. Additionally, a recall throttle is computed based on the cache free space and a number of storage devices reserved for recalling data files from the set of storage volumes.

Abstract: Data is migrated from source media to target media in an automated tape library, where identifiers associated with the data are obtained from the source media, and the data and associated identifiers are consolidated by storing data/identifier paris in substantially continuous form or the target media. A plurality of source media units, such as magnetic tape cartridges, are first loaded to the library. Each source media unit contains one or more data blocks and a machine-readable identifier associated with each data block. The machine-readable identifier, for example, may be embodied by a machine-readable code imprinted on a housing of the media unit, or a code stored on the media itself. The identifier for each data block is obtained using the corresponding source media. Multiple data blocks and identifiers may be consolidated onto a single output media unit.

Abstract: Virtual data storage cartridges are created on a data storage subsystem to/from which volume writes and reads are directed. When a number of data volumes have been written, the controller may migrate them to the tape drive, a much faster process than writing directly to tape and enabling multiple logical volumes to be written to a single physical tape. With the present invention, virtual scratch cartridges are virtually premounted in a virtual drive loader while the virtual drive is accessing another virtual cartridge. When the host calls for a new scratch cartridge, it can be mounted in the virtual drive almost immediately, having already been virtually pre-loaded.