A system and method for maintaining logically consistent backups using minimal data transfer are presented A system comprises a backup system having a backup storage device and one or more primary systems having mass storage devices that are to be backed up on the backup storage device The primary systems identify changes that are going to be made to the mass storage device The combined effected locations in the mass storage device of these identified changes are then captured in a static snapshot when the mass storage device is in a logically consistent state Only those data blocks changed since the last backup are then transferred to backup system The backup system can then store these changes or apply the changes to the backup storage device in order to bring the backup storage device current to a particular point in time

Backup system that takes a snapshot of the locations in a mass storage device that has been identified for updating prior to updating

A method and apparatus for generating first and second tree topologies for any source node in a network which can be represented as a node or an edge redundant graph, such that any node in the graph remains connected to the source node via at least one tree even after the failure of a node or an edge. This technique provides a recovery mechanism upon detection of a failure in a network.

Method and apparatus for automatic protection switching

A parallel local area network server is capable of sharing data and routing messages between workstations in a local area network. An apparatus according to the invention includes a plurality of processing nodes, each constituted by at least a single data processor, and an interconnect by which the processing nodes communicate. A plurality of mass storage devices are associated with the processing nodes, and a plurality of workstation computers are connected to the processing nodes. Each processing node includes is adapted to route messages to workstation computers associated with other processing nodes and to access data located both locally and at data storage devices associated with other processing nodes. A method according to the invention includes receiving a message at a first processing node and determining if the message is directed to a workstation computer at a second processing node and sending the message to the second processing node for subsequent delivery to the workstation computer. If the message includes a request for a specific data, a second determination is made if the specific data is in the local cache memory of the first processing node. If the specific data is not in the local cache memory, determination is made if the specific data is in a mass storage device at the first processing node, and if so the mass storage device is accessed to obtain the specific data. If the specific data is not in the local mass storage device, a message is forwarded to a remote processing node to request the specific data. Once this data is obtained, it is sent to the requesting workstation computer. The network server system according to the invention thus provides the functions of a file server and a local area network switch, thereby eliminating performance limitations associated with overloaded connections between file servers and LAN switches in conventional local area networks.

Apparatus and method for sharing data and routing messages between a plurality of workstations in a local area network

A system and method for providing a static snapshot, or image, of data stored on a mass storage system are disclosed. First, a preservation memory is cleared and a virtual device is created. Whenever a write is to be performed on the mass storage system, a check is made of the preservation memory to determine if it contains a block associated with the mass storage write address. If there is not, a copy of the block in the mass storage system at the block write address is placed in the preservation memory. Whenever a read is to be performed on the virtual device, a check is made of the preservation memory to determine if it contains a block associated with the virtual device read address. If there is such a block, that block is returned as the result of the virtual device read. Otherwise, the block at the virtual device block read address is returned as the result.

Method and system for providing a static snapshot of data stored on a mass storage system

A real time fault tolerant transaction processing system, particularly one suited for use in a service control point (SCP), is described. Specifically, the system utilizes a communication protocol, such as signalling system 7, that adaptively distributes message packets on an equal basis over multiple physical links that connect two points, such as an SCP and a signalling transfer point (STP), and non-fault tolerant front end and back end processors that are connected to each physical link for processing packets appearing on that link and providing corresponding responses thereto. All the front and back end processors are loosely coupled together for purposes of processor synchronization and re-assignment. Through this system, all the physical links simultaneously carry an equal number of packets which are, in turn, processed by all the processors connected thereto. In the event any physical link or either a front or back end processor connected thereto fails, then that link is declared to be out of service. Consequently, the protocol merely re-assigns all subsequently occurring packets to the other links until such time as the fault is cleared. As the result of link re-assignment, there is advantageously no need to connect a fault tolerant processor to each physical link. This, in turn, substantially and advantageously reduces the complexity and cost of the fault tolerant transaction processing system.

Real time fault tolerant transaction processing system

A fault-tolerant computer system provides information transfers between the units of a computing module, including a processor unit and a memory unit and one or more peripheral control units, on a bus structure common to all the units. Information-handling parts of the system, both in the bus structure and in each unit, can have a duplicate partner. Error detectors check the operation of the bus structure and of each system unit to provide information transfers only on fault-free bus conductors and between fault-free units. The computer system can operate in this manner essentially without interruption in the event of faults by using only fault-free conductors and functional units. Arbitration circuits of unusual speed and simplicity provide units of the computing module with access to the common bus structure according to the priority of each unit. The units of a module check incoming and outgoing signals for errors, signal other module units of a detected error, and disable the unit from sending potentially erroneous information onto the bus structure.

Digital data processor apparatus with pipelined fault tolerant bus protocol

FAULT-TOLERANT COMPUTER SYSTEM ABSTRACTA fault-tolerant computer system provides information transfers between the units of a computing module, including a processor unit and a memory unit and one or more peripheral control units, on a bus structure common to all the units. Information-handling parts of the system, both in the bus structure and in each unit, can have a duplicate partner. Error detectors check the operation of the bus structure and of each system unit to provide information transfers only on fault-free bus conductors and between fault-free units. The computer system can operate in this manner essentially without interruption in the event of faults by using only fault-free conductors and functional units. Arbitration circuits of unusual speed and simplicity provide units of the computing module with access to the common bus structure according to the priority of each unit. The units of a module check incoming and outgoing signals for errors, signal other module units of a detected error, and disable the unit from sending potentially erroneous information onto the bus structure.

Digital data processor with high reliability

A fault-tolerant computer system (10) provides information transfers between the units of a computing module, including a processor unit (12) and a memory unit (16) and one or more peripheral control units (20, 24, 28), on a bus structure (30) common to all the units. Information-handling parts of the system, both in the bus structure and in each unit, can have a duplicate partner (14, 18, 22). Error detectors check the operation of the bus structure and of each system unit to provide information transfers only on fault-free bus conductors and between fault-free units. The computer system can operate in this manner essentially without interruption in the event of faults by using only fault-free conductors and functional units. Arbitration circuits of unusual speed and simplicity provide units of the computing module with access to the common bus structure according to the priority of each unit. The units of a module check ncoming and outgoing signals for errors, signal other module units of a detected error, and disable the unit from sending potentially erroneous information onto the bus structure.

Computer peripheral control apparatus

A multinodal system is one-way interconnected, two-way interconnected or, more generally, (n)-way interconnected, where (n) is an integer. In a one-way interconnected system, only one connection element couples any two nodes. Or, put another way, only one communication path exists between every node and every other node. A two-way interconnected system, on the other hand, has two connection elements coupling each pair of nodes. Likewise, an (n)-way interconnected system provides (n) independent connection paths between each pair. Such systems are characteristic in that the relationship between the number of independent buses (b), the number of nodes (v), the number of ports (r), and the degree of interconnectedness (n) can be expressed by the equation ##EQU1## Two-way and (n)-way interconnect arrays may be adapted for use in fault-tolerant communications.

Optimized interconnect networks

A fault-tolerant computer system (10) provides information transfers between the units of a computing module, including a processor unit (12) and a memory unit (16) and one or more peripheral control units (20, 24, 28), on a bus structure (30) common to all the units Information-handling parts of the system, both in the bus structure and in each unit, can have a duplicate partner (14, 18, 22) Error detectors check the operation of the bus structure and of each system unit to provide information transfers only on fault-free bus conductors and between fault-free units The computer system can operate in this manner essentially without interruption in the event of faults by using only fault-free conductors and functional units Arbitration circuits of unusual speed and simplicity provide units of the computing module with access to the common bus structure according to the priority of each unit The units of a module check ncoming and outgoing signals for errors, signal other module units of a detected error, and disable the unit from sending potentially erroneous information onto the bus structure

Kurt F. Baty

Papers

Digital data processor apparatus with pipelined fault tolerant bus protocol

Digital data processor with high reliability

Computer peripheral control apparatus

Optimized interconnect networks

Digital data processor with high reliability and method