Abstract: A method, system, apparatus and computer program product for determining an optimal file operational time in a data storage system for use with a tape media storing data in a serpentine pattern on tape media is provided. The operational time is optimized based on a “sequence on tape” algorithm, a “minimum reversal of direction on tape” algorithm, or a “minimum delay to next data” algorithm. A model is used to determine the predicted performance of each of the algorithms, and the algorithm that provides the minimum overall operational time is chosen and applied for carrying out an operational process on the tape media.

Abstract: A method for throttling host throughput in a computer storage subsystem is provided. The host throughput is compared to a throughput limit for a predetermined time period. If the host throughput exceeds the throughput limit during the predetermined time period, an input/output (I/O) delay is set equal to the remainder of the predetermined time period, and the delay is implemented for an associated storage device of the computer storage subsystem.

Abstract: A method and apparatus for handling multi-volume datasets in a tape storage system are disclosed. In response to a write request for a multi-volume dataset, the information of the multi-volume dataset are captured by intercepting and deciphering a set of volume mount commands. Otherwise, the information of the multi-volume dataset are captured by snooping header information from a previous volume listed in a header of the multi-volume dataset. A chain of logical volume names that belongs to the multi-volume dataset is then built. Finally, the chain of logical volume names is then stored in a chain database.

Abstract: A method for providing continuous access to shared tape drives from two virtual tape server (VTS) nodes is disclosed. A group of tape drives are connected to two VTS nodes via a set of switches. Both VTS nodes can concurrently process requests to mount physical tape cartridges to separate tape drives. The selection of a tape drive to fulfill a volume mount request on a physical volume begins by locking down any access to a tape drive table having a composite view of all the tape drives shared between the two VTS nodes. An available tape drive is then selected to mount the physical volume, and an entry in the tape drive table is updated to claim ownership of the tape drive. A reservation command is sent to the tape drive to lock down any access to the tape drive, and the lock to the tape drive table is released. Having claimed ownership to the tape drive, the VTS node can now perform the volume mount request.

Abstract: An apparatus, system, and method are disclosed for selecting a source cluster in a distributed storage configuration. A measurement module measures system factors for a plurality of clusters over a plurality of instances. The clusters are in communication over a network and each cluster comprises at least one tape volume cache. A smoothing module applies a smoothing function to the system factors, wherein recent instances have higher weights. A lifespan module calculates a mount-to-dismount lifespan for each cluster from the smoothed system factors. A selection module selects a source cluster for accessing an instance of a specified volume in response to the mount-to-dismount lifespans and a user policy.

Abstract: A virtual tape server for executing a method involving a partitioning of a virtual tape volume into a plurality of virtual tape blocks. The virtual tape volume includes a virtual tape volume header having recovery information, each virtual tape block includes a virtual tape block header identifying the virtual tape volume and a block sequence number, and one or more of the virtual tape blocks includes the virtual tape volume header. The method further involves a formatting of a physical tape volume including each virtual tape block.

Abstract: A virtual tape server for implementing a method for exporting one or more logical volumes contained in a source physical volume pool. The method involves an activation of an export clone pool to clone an identity of the source physical volume pool into the export clone pool based on the logical volumes, an exportation of the export clone pool including the logical volumes subsequent to the activation of the export clone pool, and a deactivation of the export clone pool to purge the identity of the source physical volume pool from the export clone pool subsequent to the exportation of the export clone pool.

Abstract: A method to write information to two geographically separated virtual tape servers, where the method provides a file to a virtual tape controller, writes that file to a first virtual tape server, and queues a copy job for the file in the virtual tape controller. Subsequently, the method provides the file to a second virtual tape server. The method sets a throughput threshold, determines the actual VTC throughput, and determines if the actual VTC throughput exceeds the throughput threshold. The method sets an age threshold and determines if the copy job age is greater than that age threshold. If the actual VTC throughput is greater than the throughput threshold and the copy job age is greater than the age threshold, then the method decreases the first adjustable host bandwidth and/or the second adjustable host bandwidth, otherwise the method restores the bandwidth to a nominal value.

Abstract: A media server (e.g., a virtual tape server) implements a method for a dynamic media format conversion of physical volumes stored within a media library (e.g., a tape library). The method involves a recall of volume data in a media format f as stored in one or more source physical volumes of a source media, and an automatic premigration of the recalled volume data in a media format f to one or more target physical volumes of a target media. The media format f is different in one or more aspects from the media format f.

Abstract: A method and system for shredding data within a data storage subsystem is disclosed. According to one embodiment, a method is provided of continually shredding data within a data storage subsystem in which all the data of a first storage element is made permanently unreadable followed by the performance of a data shred process. In the described data shred process, second storage element is first selected (e.g., from plurality of candidate or potential storage elements), which includes a first storage object to be preserved and a second storage object to be shredded. Once the second storage element is selected, data of the first storage object is stored/copied within the first storage element. Thereafter, all data of the second storage element is rendered permanently unreadable.

Abstract: A device monitors a system's available resources and produces either a deferred notification or an instant notification based on a comparison with an established threshold. The threshold may be adjusted if current or anticipated system resource utilization changes. Changes to the threshold may result in deferred notifications being removed from a queue and an instant notification being transmitted to a reporting facility.

Abstract: A system and method for guaranteeing overwrite of expired data in a media device, the data being organized according to logical units provided on media devices organized as physical volumes. The method comprises the steps of: maintaining information associated with a status of a physical volume, and updating a physical volume's status information based upon a combination of that volume's prior status and that volume's current status; specifying a time duration that expired logical unit data may remain on a physical volume; based upon the volume's updated status information, determining whether a selected volume has expired data longer than the specified time duration; and, overwriting contents of the volume having data that has expired longer than the specified time duration.

Abstract: A method to form one or more premigration aggregates comprising a plurality of least recently accessed virtual volumes disposed in an information storage medium. The method determines the number (R) of virtual volumes to remove from the information storage medium, selects the (R) least recently accessed virtual volumes, forms one or more premigration aggregates comprising those least recently accessed virtual volumes, and assigns each of the (R) selected virtual volumes to one of those premigration aggregates. The method establishes a minimum transfer size and determines if any of the premigration aggregates are larger than that minimum transfer size. The method writes to one or more physical volumes each of the premigrate aggregates that are larger than the minimum transfer size. Thereafter, the method removes from the information storage medium each of the premigration aggregates written to physical volumes.

Abstract: A method to assign a premigration pseudotime attribute and a stubbing pseudotime attribute to a logical volume. The method defines a plurality of host requests, and associates with each host request a pseudotime range. The method further maintains a logical volume in a first information storage medium at a first time, and determines if a user provides a host request for that logical volume. If a user provides a host request for that logical volume, then the method assigns to the logical volume a premigration pseudotime attribute, and a stubbing pseudotime attribute, comprising a time within the pseudotime range associated with the host request. If, on the other hand, a user does not provide a host request for the logical volume, then the method assigns to that logical volume the first time as said premigration pseudotime attribute, and said first time as said stubbing pseudotime attribute.

Abstract: A method and apparatus for maintaining information in one or more virtual volume aggregates comprising a plurality of virtual volumes. The method maintains a plurality of virtual volumes in a first information storage medium, and forms one or more virtual volume aggregates, where each of the of virtual volumes is assigned to one of the virtual volume aggregates. The method further provides a plurality of second information storage media. The method then identifies the least recently used virtual volume, and writes the virtual volume aggregate comprising that least recently used virtual volume to one or more second information storage media. Thereafter, the method determines if space is required on said first information storage medium.

Abstract: A method to write information to one or more information storage media disposed in a data storage and retrieval system comprising host adapters capable of data compression and information storage devices capable of data compression. The method establishes a storage medium usage threshold and determines the actual storage media usage level for the data storage and retrieval system. The method then determines if the actual storage media usage level is greater than the storage medium usage threshold. If the actual storage media usage level is greater than said storage medium usage threshold, then the method enables use of information storage device data compression. Alternatively, if the actual storage media usage level is not greater than said storage medium usage threshold, then the method disables use of information storage device data compression.

Abstract: A method to form one or more premigration aggregates comprising a plurality of least recently accessed virtual volumes disposed in an information storage medium. The method determines the number (R) of virtual volumes to remove from the information storage medium, selects the (R) least recently accessed virtual volumes, forms one or more premigration aggregates comprising those least recently accessed virtual volumes, and assigns each of the (R) selected virtual volumes to one of those premigration aggregates. The method establishes a minimum transfer size and determines if any of the premigration aggregates are larger than that minimum transfer size. The method writes to one or more physical volumes each of the premigrate aggregates that are larger than the minimum transfer size. Thereafter, the method removes from the information storage medium each of the premigration aggregates written to physical volumes.

Abstract: A method to assign a premigration pseudotime attribute and a stubbing pseudotime attribute to a logical volume. The method defines a plurality of host requests, and associates with each host request a pseudotime range. The method further maintains a logical volume in a first information storage medium at a first time, and determines if a user provides a host request for that logical volume. If a user provides a host request for that logical volume, then the method assigns to the logical volume a premigration pseudotime attribute, and a stubbing pseudotime attribute, comprising a time within the pseudotime range associated with the host request. If, on the other hand, a user does not provide a host request for the logical volume, then the method assigns to that logical volume the first time as said premigration pseudotime attribute, and said first time as said stubbing pseudotime attribute.

Abstract: A method and apparatus for maintaining information in one or more virtual volume aggregates comprising a plurality of virtual volumes. The method maintains a plurality of virtual volumes in a first information storage medium, and forms one or more virtual volume aggregates, where each of the of virtual volumes is assigned to one of the virtual volume aggregates. The method further provides a plurality of second information storage media. The method then identifies the least recently used virtual volume, and writes the virtual volume aggregate comprising that least recently used virtual volume to one or more second information storage media. Thereafter, the method determines if space is required on said first information storage medium.

Abstract: A system and method for guaranteeing overwrite of expired data in a media device, the data being organized according to logical units provided on media devices organized as physical volumes. The method comprises the steps of: maintaining information associated with a status of a physical volume, and updating a physical volume's status information based upon a combination of that volume's prior status and that volume's current status; specifying a time duration that expired logical unit data may remain on a physical volume; based upon the volume's updated status information, determining whether a selected volume has expired data longer than the specified time duration; and, overwriting contents of the volume having data that has expired longer than the specified time duration.