Abstract: A network file server includes a first set of data processors for receiving requests from clients, and a second set of data processors for accessing read-write file systems. A respective data processor in the second set is assigned to each file system for exclusive management of locks on the file system. The file server can detect failure of a failed data processor and automatically recover from the failure. When a failure of a data processor in the first set is detected, a spare data processor is programmed with the logical and physical network addresses of the failed data processor so that the spare data processor assumes the network identity of the failed data processor. When a failure of a data processor in the second set is detected, responsibility for management of the locks on each file system managed by the failed data processor is transferred to an operational data processor.

Abstract: A digital computer system includes a master mass storage subsystem and a slave mass storage subsystem which provides mirrored storage for the master mass storage subsystem. One or more host computer systems can access information in the master mass storage subsystem to retrieve information from, and update information stored in, the master mass storage subsystem. When a host computer accesses information in the master mass storage subsystem, the information is cached in the master mass storage subsystem's cache memory, and when the information is updated, the update information will be updated in both mass storage subsystem's cache memories prior to being stored in their respective storage devices.

Abstract: A method and apparatus for providing very large logical volumes (Meta Device) in a storage system is provided. The storage system includes host controllers and disk controllers which communicate through a shared memory. I/O requests are received by the host controller and placed into request queues. The request queues are associated with logical devices. A number of request queues in the host controller are concatenated together to produce the larger logical volume. The large logical volume appears to the host as a single addressable logical unit. I/O requests to the large logical volume are analyzed by the host controller to determine which logical devices are actually needed to service the request. The host controller then makes the appropriate queue entries. Processing of the requests then occurs in the same fashion as if the request had been to a non-Meta Device. This allows the disk controllers and memory to operate without modification.

Abstract: An apparatus for capturing data transmitted over of a plurality of bi-directional communication buses is provided. The apparatus comprises a plurality of trace engines, each trace engine having a trace analyzer and a central processing unit connected together with a bus. Each one of the trace engines is connected to another trace engine, so that all of the trace analyzers within the trace engines are synchronized to a common clock. The synchronization to a single common clock allows all of the data captured by the plurality of trace engines to be analyzed or used together.

Abstract: A digital computer system comprises a mass storage subsystem and an “open systems” computer system. The mass storage subsystem includes a storage device for storing data and an access control for performing an access operation in connection with the storage device in response to a channel program received thereby in at least one channel program information transfer packet. The channel program includes at least one channel command and the supplementary channel command processing information useful in processing the at least one channel command. The “open systems” computer system performs processing operations in response to programs.

Abstract: A stacked map storage system has a base mapping of logical data to physical locations in the storage system. Level maps are created either as positive or negative maps of a lower level map. A positive map enables an alternate view while keeping the next lowest level map the same. A negative map allows changes to a lower level map but stores references to the data in itself so the negative map becomes a backup. Negative maps freeze storage in themselves and are read-only. A positive map allows changes to itself and can be used by applications under test to make changes, while not allowing changes to the next lower level map to be made through the positive map. In a preferred embodiment, maps can be stacked to any number of levels, can be shared by applications and hosts, and can either be deleted or merged. Deletion removes the map as though it never existed. A merge overlays an upper view onto a lower view and thus changes the lower view to match the other's state.

Abstract: A semiconductor interconnect structure which includes a semiconductor substrate having a bottom surface. The printed circuit board also has a plurality of solder wettable pads disposed on the top surface of the printed circuit board. The printed circuit board and the semiconductor substrate are both comprised of material taken from the same group of materials. The interconnect structure also includes a plurality of balls formed of a first solder alloy disposed on the bottom surface of the semiconductor substrate and projecting downwardly therefrom. Each one of the plurality of balls are sized to support the weight of the semiconductor substrate. The interconnect structure also includes a plurality of solder joints formed of a second solder alloy connecting the plurality of balls to the corresponding plurality of wettable pads on the printed circuit board.

Abstract: A method of dynamically reconfiguring the logical devices in a storage system is provided. The method allows a logical devices to be added, removed, or repositioned without requiring the storage system to be taken off-line. The method includes manipulating the request queues associated with host controllers within the storage system. The request queues associated with each logical device may be repositioned in the request queue memory in order to make room for new logical devices or to take advantage of free space associated with a removed logical device. The storage system communicates with the host computer in order to manage the reconfiguration of the request queues while still providing storage services to the host computer.

Abstract: An apparatus for defragmenting disks by incorporating a copy function in the logic controlling a disk, so that a disk can be instructed to copy the contents of tracks from one area to another on the disk without requiring a series of data transfers between the disk and the host computer to which it is assigned. Conventional defragmentation techniques can be used to determine which files need to be defragmented and how much contiguous free space is available on the disk. Once this has been determined, the present invention enables the defragmentation program to send copy commands to the disk to cause the copy function in the logic controlling the disk to perform the data transfers, thus freeing up the host computer to perform other processing until the logic controlling the disk signals completion of the copy function's operation.

Abstract: A digital data processing system comprises a host information generating device, a mass storage subsystem, and a back-up information storage subsystem. The host information generating device generates information and provides it to the mass storage subsystem for storage. The mass storage subsystem receives the generated information from the host information generating device and transfers the generated information to the storage element for storage, and further transfers the generated information to the back-up information storage subsystem. The back-up information storage subsystem receives and stores the generated information from the mass storage subsystem's control element. The back-up information storage subsystem includes a filter/buffer module, a tape log module and a reconstruction module. The filter/buffer module filters and buffers the information received from the mass storage subsystem and provides the buffered information to the tape log module for storage.

Abstract: A network file server includes a first set of data processors for receiving requests from clients, and a second set of data processors for accessing read-write file systems. A respective data processor in the second set is assigned to each file system for exclusive management of read and write locks on the file system. Each data processor in the first set can authorize access to file systems directly accessed by more than one data processor in the second set. Processing of a request for access that is authorized is continued by the data processor that is assigned to manage the locks on the file system to be accessed. The exclusivity of lock management eliminates cache coherency problems, and dynamic load balancing can be used to prevent the lock management from becoming a bottleneck to performance. A preferred embodiment includes a cached disk storage subsystem linked to data mover computers.

Abstract: A digital computer system comprises a mass storage subsystem and an “open systems” computer system. The mass storage subsystem includes a storage device for storing data and an access control for performing an access operation in connection with the storage device in response to a channel program received thereby in at least one channel program information transfer packet. The channel program includes at least one channel command and the supplementary channel command processing information useful in processing the at least one channel command. The “open systems” computer system performs processing operations in response to programs.

Abstract: An address triggered DMA controller includes a DMA engine for controlling transfer of data between an external device and locations in a memory designated by respective addresses. Such a DMA controller also includes a DMA monitor for monitoring the respective addresses, and if one of the respective addresses matches a predetermined value, generating a signal to indicate a match.

Abstract: A file management system is disclosed for managing files stored on a mass storage subsystem in response to file management commands. The mass storage subsystem stores data on at least one storage device, said storage device including a series of blocks. The file management system comprises an operating system-independent file map, a file management command receiver module, and a file management command execution module. The operating system-independent file map stores information identifying, for each file, block information identifying blocks on which the file is stored. The file management command receiver module receives a file management command. The file management command execution module executes the file management command in relation to the operating system-independent file map.

Abstract: A method of dynamically changing a storage system from a RAID configuration to a mirror configuration is provided. The change occurs when a device begins to fail or fails completely. Data from the logical volumes of the failed device is written to corresponding parity volumes within the RAID group. In addition, data from all logical data volumes is copied to spare devices. Once all the data is copied, the system operates in a mirrored mode. A mirrored mode includes writing data to both and active and backup volume for each write transaction. When the failed device is replaced the data and parity volumes are restored. Once restored, the spare devices are returned to inactive status.

Abstract: A digital data processing system comprises a host information generating device, a mass storage subsystem, and a back-up information storage subsystem. The host information generating device generates information and provides it to the mass storage subsystem for storage. The mass storage subsystem receives the generated information from the host information generating device and transfers the generated information to the storage element for storage, and further transfers the generated information to the back-up information storage subsystem. The back-up information storage subsystem receives and stores the generated information from the mass storage subsystem's control element. The back-up information storage subsystem includes a filter/buffer module, a tape log module and a reconstruction module. The filter/buffer module filters and buffers the information received from the mass storage subsystem and provides the buffered information to the tape log module for storage.

Abstract: A method and apparatus for providing very large logical volumes (Meta Device) in a storage system is provided. The storage system includes host controllers and disk controllers which communicate through a shared memory. I/O requests are received by the host controller and placed into request queues. The request queues are associated with logical devices. A number of request queues in the host controller are concatenated together to produce the larger logical volume. The large logical volume appears to the host as a single addressable logical unit. I/O requests to the large logical volume are analyzed by the host controller to determine which logical devices are actually needed to service the request. The host controller then makes the appropriate queue entries. Processing of the requests then occurs in the same fashion as if the request had been to a non-Meta Device. This allows the disk controllers and memory to operate without modification.

Abstract: A method of managing shared storage system resources amongst a plurality of heterogeneous host computers utilizing different operating systems is described. The method includes providing a lock mechanism which allows a host to gain exclusive control of storage system resources, including storage devices.

Abstract: Arrangements are disclosed for use in a network of digital data processing systems for rapidly encoding information signals for transmission over communication links in the network, and for rapidly decoding information received thereover, thereby to facilitate higher-bandwidth communications over the network. In addition, network command and control information transmitted along in the data transmitted over the network is rapidly decoded and verified by a command decoder and command verifier.

Abstract: A clock distribution system in a reliable electronic system includes a predetermined number of clock signal load circuits, each having a clock signal input terminal. A first clock signal generator has the same predetermined number of clock signal output terminals coupled to the clock signal input terminals of the clock signal load circuits. A second clock signal generator also has the same predetermined number of clock signal output terminals which are also coupled to the clock signal input terminals of the clock signal load circuits.