Abstract: Provided are a method, system, and article of manufacture for borrow processing in storage pools. A plurality of physical volumes are allocated to a first storage pool. A determination is made whether the first storage pool has less than a threshold number of empty physical volumes. If the first storage pool has less than the threshold number of empty physical volumes, then at least one empty physical volume is borrowed to the first storage pool from a second storage pool.

Abstract: Provided are a method, system, and article of manufacture for pooling of storage. Volume attributes are assigned to a plurality of physical volumes. Pool attributes are assigned to a plurality of storage pools, wherein the pool attributes include policies for borrowing and returning the plurality of physical volumes to and from the plurality of storage pools. One of the plurality of physical volumes is allocated to one of the plurality of storage pools based on the volume attributes of the one of the plurality of physical volumes and the pool attributes of the one of the plurality of storage pools.

Abstract: Provided are a method, system and article of manufacture for return processing in storage pools. A plurality of physical volumes are allocated to a first storage pool. A determination is made whether the first storage pool has more than a threshold number of empty physical volumes. If the first storage pool has more than the threshold number of empty physical volumes, then at least one empty physical volume is returned to a second storage pool.

Abstract: A method to schedule and perform database maintenance, where the database includes information regarding one or more information storage media moveably disposed in a data storage and retrieval system, which includes selecting a first time period, commencing that first time period at a first time and ending that first time period at a third time, performing one or more database queries during that first time period, recording the number of database queries performed during each of the two or more first time intervals, determining the least utilized first time interval where that least utilized first time interval commenced at a second time, calculating a first time difference between the first time and the second time, and scheduling database maintenance at a fourth time. A data storage and retrieval system comprising a computer useable medium having computer readable program code disposed therein to implement Applicants' method to schedule and perform database maintenance.

Abstract: A transaction processing system that continues to process incoming transactions during the failure and recovery of either of two duplicate databases. One of the two duplicate databases is assigned “active” status and the other is maintained with “redundant” status. All incoming queries are sent only to the active database and all incoming updates are sent to both active and redundant databases. When one database fails, the other is immediately reassigned active status if not already active and continues to process incoming queries and updates during the failure. When the failed database is repaired and restarted, all records are flushed therefrom and the failed database is reconstructed using interleaved copy and update operations in a single pass through the active database. Incoming transaction and copy operations are interleaved according to a queue thresholding method for throttling copy operations responsive to increased numbers of incoming transactions.

Abstract: Digital data records are stored on a direct access storage device (DASD) in emulation of sequential-access media, the efficiency of storage and access of the data being improved by using a volume trailer containing various statistics about the records. Data is preferably stored in records, logically assembled into record groups. 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 contains pointers to each record group, record counts for each group, marker code counts for each group, and may also include fields showing whether records in a given record group are of equal length. The volume trailer may also include a volume trailer “tail”, including a byte count for the entire volume trailer, and a unique sequence identifying the volume trailer. Statistics contained in the volume 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 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 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: Digital data records are stored on a direct access storage device (DASD) in emulation of sequential-access media, the efficiency of storage and access of the data being improved by using a volume trailer containing various statistics about the records. Data is preferably stored in records, logically assembled into record groups. 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 contains pointers to each record group, record counts for each group, marker code counts for each group, and may also include fields showing whether records in a given record group are of equal length. The volume trailer may also include a volume trailer "tail", including a byte count for the entire volume trailer, and a unique sequence identifying the volume trailer. Statistics contained in the volume trailer enable substantially more efficient access of the data by a DASD.

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: 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.