Unisys Corporation

Sperry Rand Corporation

Ralph E Sipple

John R Jordan

Dennis R Konrad

Thomas P Cooper

Wayne D Ward

James M Plasek

James R McBreen

Michael J Hill

Michael F Stanton

Ronald Q Smith

Anthony P vonArx

James A Elke

Lester Y Lee

James R Mettling

David R Johnson

Robert E Swenson

Michael J Heideman

Lee-Chin Hsu Liu

James F Torgerson

Jennifer J Smith

Joseph E Kessler

Lee B Hansen

Marvin W Theis

Rajeev P Tandon

Michael J Bierma

Bruce T Kunz

John O Sjolander

Robert F Esson

Donald T Bordsen

Donn B Baker

Katsuhiko Kihara

Sheng-te Chiang

A method of and apparatus for efficiently providing video on demand services to a cable television subscriber. The provider system consists of two major subsystems. The first subsystem, called a video server, streams video to video on demand subscribers through the cable television network. The second subsystem, called the transaction server, performs virtually all remaining provider functions including, security, accounting, storage and spooling of video data, etc. The video server is preferably uses a Unisys CMP memory platform into which the transaction server spools requested video programs. One or more industry standard processors operating under a standard operating system stream the video data from the memory platform to the subscriber.

Video server

A method of and apparatus for efficiently providing video on demand services to a cable television subscriber. The provider system consists of two major subsystems. The first subsystem, called a video server, streams video to video on demand subscribers through the cable television network. The second subsystem, called the transaction server, performs virtually all remaining provider functions including, security, accounting, storage and spooling of video data, etc. The transaction server preferably uses a large scale mainframe computer. The video server subsystem may be a partitioned portion of same large scale mainframe computer.

Video on demand transaction server

Multi-processor computer systems with multiple levels of cache memories are slowed down in trying to process software locks for common functions. This invention obviates the problem for the vast majority of transactions by providing an alternate procedure for handling so-called communal locks differently from ordinary software locks. The alternative procedure is not used for ordinary (non communal software lock) data and instruction transfers. The function of the CSWL (Communal SoftWare Lock) is actually accomplished at a specific cache to which an individual CSWL is mapped to, rather than sending the lock to the requesting process, which also enhances efficiency.

Method for processing communal locks

In order to implement alternative pathways and procedures for handling a separate set of software locks, an arrangement of circuits is described. These circuits allow for generating and handling specific requests for communal software locks without additional software development through pathways and procedures separate from ordinary lock handling operations. A side door communications pathway is set up to handle the communal locks separately from the ordinary data transfer pathways through which ordinary software locks get handled. Supporting and controller circuits handle the locking and unlocking process as well as communicating results of lock requests back to requesters.

Communal lock processing system for multiprocessor computer system

Multi-processor computer systems with multiple levels of cache memories are given an alternate pathway for handling highly contended-for locks. These are called communal locks. The alternate pathway allows for alternate processing schemas that do not impede the performance of the overall system as is otherwise the case in such computer systems where contended-for locks bounce back and forth between contending caches, crimping storage bus bandwidth and system performance. The alternative pathway is not used for ordinary (non communal software lock) data and instruction transfers.

Multiprocessor computer system for processing communal locks employing mid-level caches

An apparatus and method of efficiently recovering from physical disk drive (or logical file) failures in transaction based digital data processing systems. As transactions are sequentially processed, compacted audit trail records are prepared to indicate modifications resulting from each transaction. The audit trail records are stored in storage areas on a disk drive in accordance with the physical data base disk drive(s) or logical file(s) to which the corresponding transaction refers. A physical disk drive or logical file is dumped to magnetic tape whenever the associated audit trail storage area is full, thus clearing the audit trail storage area for further use. When a physical disk drive or logical file fails, the most recent dump is read. Modifications to each file of the dump are made as compacted audit trail data is processed. The modified files are destaged to a spare disk drive.

Disk recovery/reconstruction

The present invention overcomes many of the disadvantages associated with the prior art by providing an automated, real time performance monitoring facility which runs periodically as a background process in a computer system. This invention preferably uses performance data collection sites already present in the hardware of the computer system, microcode and/or operating system software. At a user selectable period of time, a sampling of key performance factors is taken from the performance data collection sites. The performance monitor then analyzes the, sampled results by comparing the collected results against two or more performance threshold levels (such as early warning or actual performance limiters) for each performance criteria. If either an actual or early warning performance limiter is detected, an easy-to-understand color coded informational message is provided to a computer operator identifying subsystems that are performance inhibitors along with suggestions of specific upgrade solutions that will address the identified performance problems.

Apparatus for and method of automatic monitoring of computer performance

A data processing system including a first and second host, a first and second outboard file cache connected to the first host, and a first and second secondary storage device connected to the first host. The system operation includes the first host reading file data from the first or second secondary storage device after the data is cached on both the first and second outboard file caches. File data is updated by writing to both first and second outboard file caches. File data is destaged by writing data from the first outboard file cache only, to first and second secondary storage devices. Failure of a single outboard file cache is handled by the first host not reading and writing to the failed outboard file cache. Site-wide failure of first host, first outboard file cache, and first secondary storage device is handled by establishing communication from second host to both second outboard file cache and second secondary storage device and resuming processing.

Dual XPCS for disaster recovery

A system and method for expediting database queries by using random sampling. Data associated with a database attribute is partitioned into multiple data classes using a query language grouping command. Each of the data classes is randomly sampled on an individual basis to obtain a corresponding number of class data samples, each of which are stored in a separate sample database table. Database queries are then applied to each of the class data samples in the sample database table.

Statistical database query using random sampling of records

A system for concurrent processing of queries and transactions against a shared database. The system includes multiple processors wherein a processor is available for processing queries and another processor is available for concurrently processing transactions. A query buffer is established for performing the query search while the data accessed by transactions is available in a database cache. Control logic in a database management system distinguishes between transactions and queries and initiates file-read control for reading the file containing the database. File-read control contains logic for logical sequential reading and logical non-sequential reading of the file. Control structures provide a means for control over the load that the query is allowed to place on the system.

System for optimally processing a transaction and a query to the same

A system for parallel reading and processing of a file. The system includes multiple disks for storing the file. The disks are coupled to a data processing system via multiple input-output channels. A file buffer is established in the memory of the data processing system, wherein the file buffer is shared by an instruction processor that initiates a parallel read request and manipulates the file data once it is read, and multiple input-output processors that are coupled to the input-output channels. Multiple input requests are issued to the multiple disks to be processed in parallel. The input-output processors write file data to a first portion of the file buffer in parallel with the reading of a second portion of the file buffer by the instruction processor. Control structures provide a means for control over the input processing demands that the parallel read request is allowed to place on the system.

System for parallel reading and processing of a file

A system and method for distributing real-time, compressed, digital video data from a video library composed of multiple mass storage devices through a digital video data server to large numbers of viewers via distribution networks is provided. The server obtains selected frames of video data for viewer-requested programs from high-speed memory using a buffering strategy, replicates the data via a multi-cast technique for each viewer listed in an assigned synchronization group and forwards the data to each viewer's site where it is decompressed, decoded, and converted for display on a television monitor or computer display. Each viewer maintains interactive control over the transmission of the digital video data.

Multi-cast digital video data server using synchronization groups

A system and method for maintaining a backup data base. An initial backup copy of a data base is made and stored separate from an active primary data base. Each time the primary data base is updated, audit information pertaining to the data base update is stored in non-volatile storage. A recovery processor continuously reads the audit information from the non-volatile storage and updates the backup data base accordingly, thereby maintaining a backup data base which is nearly up-to-date with the primary data base.

Data base backup and recovery system and method

A multiprocessor data processing system is implemented with processors, each of which may request for a temporary time the exclusive lock on an object which is stored on a data base. To achieve this a lock processor synchronizes the locking and unlocking of the objects. The requesting processor directs the storage of the object from the data base into a selected high performance storage unit, where it has exclusive rights to modify or write into the object until the object is unlocked by the processor. An audit tape or disk records all modifications made to any object during a transaction. A non-volatile cache memory is inserted in the audit trail to store a before-look image of the object that resides in the high performance storage unit. Data compaction occurs by comparison of the before-look image with an after-look image to provide a difference image, which is supplied to an audit buffer that is coupled to the audit tape. The locking processor may unlock the secured object once the after-look image has been committed from either a stored version in the non-volatile cache or from a high performance main memory unit to the data base disk. The difference image and the after-look image associated with the difference image may then be stored in the non-volatile cache, and provided to the audit tape or disk and the data base disk in a sequence which is independent of the operating sequence of the requesting processor.

Cache memory with data compaction for use in the audit trail of a data

A record lock processor provides a common facility for control of the locking and unlocking of mass storage objects (for example, records, files, pages or any other logical entity) that is shared by a number of loosely-coupled data processors. The terms 'record' or 'records' wherever they are used in this document are intended to refer to all such objects, including records, files, pages or any other logical grouping or entity into which the mass storage may be portioned. Each of the data processors has access to all of the shared mass storage. Three Lock Modules all receive the same requests and majority voting techniques are used to determine the result. A fourth lock module is included as a Hot Spare Module. A Maintenance Module receives the same requests as the voting Lock Modules and, therefore, it is able to interpret results on-line based on user requests. Programmable Channel Interfaces provide the operational interface to the host processors. The Lock Modules are also programmable, and they hold lock and Queued Lock Requests and execute locking and unlocking algorithms in response thereto.

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Shoreview, MN, United States of America

Ralph E Sipple