Abstract: Provided are a method, system, and program for managing storage units. Storage pool information indicates an assignment of a plurality of storage units to a plurality of storage pools, wherein each pool is assigned zero or more storage units, and wherein data associated with one storage pool is stored in at least one storage unit assigned to the storage pool. User selection is received to move at least one storage unit to a target storage pool. A determination is made of at least one storage unit assigned to a source storage pool to move to the target storage pool. The storage pool information is updated to indicate the determined at least one selected storage unit as assigned to the target storage pool.

Abstract: A system, method, and apparatus are provided for copying a virtual volume to multiple physical volumes within a virtual tape system. The virtual tape system may include a virtual tape server (VTS), a library manager, and a plurality of tape drive units into which cartridges may be individually mounted. The virtual tape system stores virtual volumes, each of which represents a physical volume, although one or more virtual volumes are actually stored on a real physical volume. The library manager contains a volume database with a plurality of constructs and associated storage management actions. The constructs are received from a host computer connected to the VTS, but the storage management actions may be entered directly into the library manager, independently of the host. The library manager reads the management action associated with one or more constructs of a virtual volume and, along with the VTS, determines whether multiple physical copies of the virtual volume are to be made.

Abstract: A system, apparatus, and method to recover a logical volume on a read-only physical volume, or data storage cartridge, within a dual copy data storage system, such as a virtual tape server (VTS) system. The recovery follows a disaster situation involving the primary physical volume and the requested logical volume. The system, apparatus, and method include modules and steps as required to recover a logical volume through recalling a selective dual copy of the logical volume stored on a secondary physical volume. The primary and secondary logical volumes are stored on distinct physical volumes in order to provide quality storage media management and reduce the likelihood of loss of data. The recovery and recall procedures are implemented in a manner that is substantially transparent and asynchronous to a host or client. Additionally, the recovery and recall require no additional input from the host in order to carry out the recovery of the logical volume.

Abstract: A method and apparatus to recover a construct definition associated with a logical volume in a virtual tape server (VTS) system following a disaster situation involving a library manager database. The method and apparatus re-establish the association between a logical volume or data file or block and a construct definition or volume attribute that assigns certain actions that may be taken on the logical volumes. Such actions and constructs may be defined by a client processor or by the VTS system in order to provide quality storage media management. The constructs may be uploaded to or reconstructed within the library manager database in combination with the host or virtual tape server and consequently made available to the system. In particular, the method and apparatus are configured to recover one or more of a storage group construct, a management class construct, a storage class construct, and a data class construct associated with a logical volume within a VTS system.

Abstract: Disclosed is a system, method, and program for transferring data. Whether data is being transferred to physical volumes in peak mode is identified. If the data is being transferred in peak mode, whether a large chain of data is available for transfer to physical volumes is determined. If the large chain of data is not available, whether a small chain of data is available for transfer to physical volumes is determined. If the small chain of data is available, the small chain of data is transferred to physical volumes. Additionally, if one or more files that have ages greater than a steady state age threshold are available, the one or more files are transferred to the one or more physical volumes. If one or more files that have ages greater than a peak age threshold are available, the one or more files are transferred to the one or more physical volumes.

Abstract: Disclosed is a system, method, and program for managing an out of available space condition. A mount command for a logical volume is received that identifies one or more physical volume pools to be subsequently used for pre-migration. It is determined that one or more of the physical volume pools have no physical volumes available for storing data. Data is prevented from being written to cache by deferring completion of the mount command until the determined one or more physical volume pools has one or more physical volumes available for storing data.

Abstract: A data storage system, employing cache and base storage, assigns an “anywhere” token to each data object received for storage, whether the object is stored in cache or base storage. The anywhere token contains the latest metadata for the data object and includes at least a version code. If a data object is stored in base storage, the data object is assigned a “base” token with the same value as its anywhere token. These “cacading” tokens are available for use in tracking functions such as cache grooming, de-staging data to base storage, and processing cache miss events. All tokens are stored in a token database. For each data object, the token database lists its anywhere token and base token. If the storage system experiences a cache failure, normal storage operations are halted until the cache is repaired. Then, the controller implements a replacement token database. Namely, the controller accesses base storage to retrieve tokens of all data objects lost from cache.

Abstract: Provided are a method, system, and an article of manufacture for optimizing storage utilization. Logical volumes are stored in a cache, wherein the cache is coupled to a plurality of physical devices. An optimum number of physical devices selected from the plurality of physical devices is determined. The logical volumes are transferred from the cache to the optimum number of physical devices.

Abstract: Messages for processing a database are protected during a termination and restart. An in-process message queue is coupled to a message reader and receives a copy of each read input message. A completion response detector monitors a valid completion response message to each read input message, and, upon detecting the valid completion response message, deletes the copied input message from the in-process message queue. Upon a termination and restart, a startup processor operates the message reader to read the input messages in the in-process message queue, and deletes the copied input message from the in-process message queue. The deletion thereby prevents any re-accessing of the copied input message upon a second restart, preventing a loop. The ease of termination and restart allows a special restart of the affected process of the database, rather than a system-wide termination and reboot.

Abstract: Provided is a method, system, and an article of manufacture for maintaining data accessible by a host in two storage devices, wherein the data is comprised of a plurality of data sets. A determination is made of a percentage of uncopied data at the first storage device, wherein uncopied data comprises data sets to be copied from the first storage device to the second storage device. If the calculated percentage is greater than a threshold amount, a rate at which uncopied data sets are transferred from the first storage device to the second storage device is increased.

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 data storage system stores data with a corresponding encapsulated metadata token in cache and/or base storage to protect against recalling stale data from base storage in the event of a cache failure and subsequent cache miss. A controller is coupled to a cache, base storage, and token database. After receiving a data object and associated write request, the controller assigns a version code to the data object. If the data object already exists, the controller advances the data object's version code. A token, including the version code along with other items of metadata, is encapsulated for storage. Then, the controller stores the data object and encapsulated token in cache and/or base storage and updates the token database to cross-reference the data object with its version code.

Abstract: A data storage library system with a plurality of data storage libraries and at least one director accesses a redundant copy of an identifiable data volume, employing the idle time status of each library to balance the workload. The data volumes may be stored in cache storage and backing storage which have different levels of access speed. A director requests a data volume, and the library controller of each library determines its current idle time status, providing the idle time status to the requesting director when it provides a synchronization token directly associated with the requested data volume. The token indicates the update level and the access level of the data volume in the library. The director, upon determining from the tokens that at least two of the copies of the data volume are at the same fastest available access level, compares the provided idle time status of the libraries storing those copies, and accesses the data volume from the library having the greater idle time status.

Abstract: Disclosed are a data storage library subsystem, and a method which may be implemented by a computer program product, for increasing the accessing performance of data volumes from libraries in a redundant copy synchronization token tracking system. The libraries store redundant copies of the data volumes, and have cache storage and backing storage. Updatable synchronization tokens indicate the relative update levels of the redundant copies. Each library maintains the synchronization token directly associated with each data volume; identifies each of the data volumes upon being stored in the cache storage of the library; and identifies each of the data volumes migrated to and stored in the backing storage of the library. Then, the library responds to a recall request for one of the redundant copies, providing, with the synchronization token, an indicator whether the data volume is identified as stored in the cache storage or the backing storage.

Abstract: The availability of cache storage is increased for data storage libraries which store redundant copies of identifiable data volumes, by migrating all but one of the redundant copies of the data volume to backing storage on a high priority basis. Each of the identifiable data volumes is directly associated with an updatable synchronization token, which is maintained by the data storage libraries. The synchronization token indicates the relative update levels of the directly associated redundant copies. For redundant data volumes having identically updated synchronization tokens, upon selection of the data storage library as primary, the library places the data volume in the cache storage at a low priority of a predetermined sequence, so that the data volume is maintained in cache storage and is migrated only on a low priority basis.

Abstract: A removable media storage library comprises a plurality of removable media divided into a plurality of sets, each set associated with its own server. A central manager controls access to all of the removable media. Each of the servers and library manager contain database map information. If this information is lost, a selected disaster recovery operation may be implemented. This flexibility in selecting the type of disaster recovery operation allows for an efficient and fast disaster recovery operation.

Abstract: A method is disclosed for automatically reconciling the client and server databases and actively management the files stored in the cache. The method monitors free space on a DASD so that a VTS is allowed to fill the DASD with data during a reconcile process. Furthermore, an active cache filename management scheme is provided that improved VTS performance by obtaining information on premigrated files thereby eliminating usage of a premigration candidate list.

Abstract: An automated reclamation scheduling system and method are taught for managing storage reclamation on a virtual tape server. Where reclamation-off times are set by a user, an automated administrator may override the settings depending on the number of scratch tapes that are available. The fewer scratch tapes that remain available, the more frequently storage reclamation will be performed in the reclamation schedule set by the automated administrator.

Abstract: A method and apparatus for improving caching for a virtual tape server is disclosed. The method and apparatus improve caching by making assumptions to increase cache hits, but which do not cause the virtual tape server to under-perform when these assumptions prove to be incorrect. The method includes the steps of correlating logical volume usage to externally determined file characteristics to derive usage histories for cached logical volumes, maintaining a record of the histories for the files that share the same predefined characteristics, and managing the migration of the logical volumes according to the usage history and the externally determined file characteristics of the logical volume.