Abstract: A data storage library features a dual purpose data/control path between a host computer and one or more media drives. The dual purpose path conveys data exchange control signals and related data between the host and drive, and also conveys robotic device management signals from the host to the drive, for ultimate conveyance to a robotic device coupled to the drive. In one embodiment, the drives may comprise relay drives, each directly coupled to the robotic device by a communications path such as a bus or loop. Alternatively, the drives may include a master drive and a number of relay drives, each relay drive coupled to the master drive to relay robotic device management signals from its host to the robotic device through the master drive. The master media drive's connection to other drives, for example, may be direct or through a communications loop interconnecting all drives.

Abstract: Data is rapidly restored from a backup copy, and user access of the restored data further expedited by providing on-demand output of logged changes to the backup data. Contents of the backup data are the same as contents of corresponding primary data at a designated time when the backup data was created. If any changes to the primary data are received by the system after creating the backup copy, the changes are stored by the system in a change log. In one embodiment, where the system stores changes in multiple logs, the logs may be consolidated and sorted according to an appropriate schedule. Whenever primary data becomes unavailable, the system starts to apply logged changes to the backup copy right away, using the consolidated and sorted change log. When the system receives user requests to access the primary data, the system determines whether the log contains any changes that have not been applied to the backup data.

Abstract: A method and apparatus determine when a subject is looking at a specific target area by estimating a divergence angle between (1) the direction in which the subject is looking and (2) the direction from the subject directly to the target area. This technique accesses whether the subject is looking at a particular area. The invention may further condition this determination according to the subject's distance from the target area, because there is less tolerance for divergent angles when the subject is farther away. In one embodiment, the divergence angle is estimated using the position of a glint of light in the subject's pupil. The glint is created by a light source located in the target area. If the glint is sufficiently central to the pupil, with the camera and light source being near the target area, the subject is looking at the target area. At long distances, when the glint is not sufficiently discernable from the pupil, another technique may be employed to estimate divergence angle.

Abstract: Any node in a multi-node processing system may be employed to route commands to a selected group of one or more nodes, and initiate local command execution if permitted by local security provisions. The system includes multiple application nodes interconnected by a network, and one or more administrator nodes each coupled to at least one application node. Each administrator node has assigned security credentials. The process starts when the administrator node transmits input to one of the application nodes (an “entry” node). The input includes a command and routing information specifying a list of desired application nodes (“destination” nodes) to execute the command. In response to this input, the entry node transmits messages to all destination nodes to (1) log-in to the destination nodes as the originating administrator node, and (2) request the destination nodes to execute the command.

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: An adjustable system for mounting data storage chassis allows chassis of differing depths to be mounted to a single set of rack mount posts. The front face of the chassis is attached to two front posts. One or more rails are then slidably inserted into the chassis and attached a corresponding number of rear posts. In one embodiment, two narrow, elongated rails are slidably adjusted into guide paths each comprising two, open and opposing brackets affixed internally to the chassis. The rails are then attached to two corresponding rear posts. In another embodiment, a single, wide rail is slidably adjusted into a single guide path at the bottom of the chassis and is then attached to one of the rear posts.

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 read/write head is provided with an embedded planar dual coil write structure. The head includes generally parallel shield, shield/pole, and pole layers. The shield/pole layer abuts a generally coplanar planarization layer in one embodiment. A circuitous recess is defined in the shield/pole and planarization layer, spanning the junction twice and encircling a central hub of adjoining shield/pole and planarization layer material. A write structure is located in the recess, with the shield/pole layer, planarization layer, and embedded write structure forming a substantially flat surface for building the pole layer. The write structure includes first and second substantially co-planar multi-turn flat coils, where turns of the first write coil are interspersed with turns of the second write coil. The first and second write coils reside in the circuitous recess, winding around the central hub. An insulating material separates the first and second coils.

Abstract: In a data storage subsystem, drive-level processing treats data storage media as WORM by automatically advancing a write append limiter as data is written, and preventing changes to data occurring before the write append limiter. Despite this media's WORM nature, the drive-level processing permits limited overwriting of data at the end of tape since the write append limiter lags the current write location by the margin of a write allowance index. Thus, despite the drive's treatment of the media as WORM, the drive permits overwriting of trailing metadata in order to facilitate write append operations.

Abstract: In a multiprocessing system, hierarchically superior configuration managers maintain profiles of operating characteristics to which subordinate managed units selectively subscribe. If the profiles or operating characteristics change, the configuration managers propagate the changes to all managed units. Each configuration manager stores a record of operating characteristics and multiple server profiles, each profile specifying one or more operating characteristics. A subscription list identifies one or more managed units, each associated with one or more server profiles. Each managed unit acts according to its current operating characteristics, stored locally at the managed unit. If the managed unit receives a profile subscription request from a system administrator, the managed unit sends a subscription message to the configuration manager to subscribe to that input profile.

Abstract: Source data is more efficiently copied to log structured target storage by pre-configuring the target storage. The invention may be practiced in a system including a host, a storage controller, and the target storage. The host maintains a directory identifying logical units of stored data, and the storage controller maintains records classifying storage space as uncollected free space, collected free space, or space-in-use. First, the host receives input including source data and specification of a logical unit for the source data. In response, the host directs the storage controller to classify any storage space of the log target storage containing data of the specified logical unit as uncollected free space. This pre-configures the log structured storage to more efficiently receive the source data.

Abstract: A track following servo system is disclosed for use with magnetic tape systems in which magnetic servo track patterns contain transitions recorded at more than on azimuthal orientation across the width of the servo track. The timing of a signal derived from reading at any point across the width of such a pattern varies continuously as the read head is moved across the servo track. The pattern is read by a servo read head whose width is small compared to the servo track pattern. The combination of a wide servo pattern and a narrow servo read head offers excellent position sensing linearity and dynamic range. In the preferred embodiment, the servo read head is also narrow with respect to the data tracks, which provides the additional advantages of superior immunity to position sensing errors caused by defects or temporal variations in the servo read head, defects in the servo pattern on the tape, wear of the head or tape, or debris collection on the head or tape.

Abstract: A system and method for storing data in a network computing environment. The network includes a source server that will receive data to be stored from a client and target servers that have locally attached physical storage media. A server-to-server protocol is used to establish a communication connection between the source server and target server while programming allows the storage of the data from the source server on the physical storage at the target server, while also creating a virtual volume at the source server on which the data is also stored. From the perspective of the client, the data appears to be stored at the source server on locally attached storage media. The present invention eliminates the requirement for actual physical media locally attached to the source server.

Abstract: A peer-to-peer backup storage system automatically switches from a primary storage site to a mirrored backup site in response to a primary site failure, where the secondary site then honors any existing host initiated reservation of primary storage. Each site includes a storage controller and storage, where the primary site receives and stores data and forwards the received data to the secondary site for storage to mirror contents of primary storage. The primary and secondary sites are coupled to one or more hosts. Whenever the primary controller receives a reserve request from a host, it reserves the primary storage (or a subpart thereof) for the exclusive use of the reserve-initiating host. This may involve, for example, the primary controller storing a path group ID that identifies the reserving host. The primary controller also notifies the secondary controller of the reservation, e.g., sending the path group ID involved in the reservation operation to the secondary site.

Abstract: A method and system for managing a multi-volume data set request in an automated storage library. The library includes automatic means for prioritizing and selecting the optimum peripheral data storage device (PDSD) for mounting a data volume belonging to the requested multi-volume data set. The optimum PDSD is that one PDSD having the closest proximity to all volumes of a multi-volume data set. The automatic means include means for determining the location of each data volume in the requested multi-volume set and means for comparing the location of each volume to the location of peripheral data storage devices. The library system employs a weighted score based on the proximity of each PDSD to each volume in a multi-volume data set to prioritize and select the optimum PDSD when a multi-volume data set is requested. Each PDSD subsystem may include one or more PDSDs.

Abstract: Print heads with arcuate printing surfaces are used to apply images to elongated, laterally curved slats prior to their assembly into Venetian blinds. Each print head includes a print head casing having a concave or convex printing surface forming an arc shape. The print heads are distributed in series along a slat path, which is defined by a conveyor. One or more ink wells are coupled to the print head casing; each ink well may contain a separate color of ink. Many print jet orifices are evenly distributed along the printing surface, and may be arranged in an array with multiple rows and columns, for example. Each print jet orifice is coupled to one of the ink wells by a supply path. During the printing process, slats are longitudinally advanced along the slat path past the print heads. A controller regulates the slat's position relative to the print heads, and controls the position using the conveyor.

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 track following servo system is disclosed for use with magnetic tape systems in which magnetic servo track patterns contain transitions recorded at more than on azimuthal orientation across the width of the servo track. The timing of a signal derived from reading at any point across the width of such a pattern varies continuously as the read head is moved across the servo track. The pattern is read by a servo read head whose width is small compared to the servo track pattern. The combination of a wide servo pattern and a narrow servo read head offers excellent position sensing linearity and dynamic range. In the preferred embodiment, the servo read head is also narrow with respect to the data tracks, which provides the additional advantages of superior immunity to position sensing errors caused by defects or temporal variations in the servo read head, defects in the servo pattern on the tape, wear of the head or tape, or debris collection on the head or tape.

Abstract: A tamper-resistant Hard-WORM data storage system and a magneto-optical storage disk therefor is disclosed. The disk has a plurality of sectors thereon containing one or more uniquely formatted fields to provide an indication that the disk is a Write-Once Read Many (WORM) disk. A motor is provided in the storage system for rotating the disk at an operational rotational speed and a laser read/write (R/W) head unit is provided for reading and writing information in the sectors. A read/write (R/W) control unit within the storage system controls read and write operations on the disk in response to commands from an external data processing device, such as a computer. The R/W control unit is adapted to decode the one or more uniquely formatted fields in order to read and correctly interpret information contained therein.